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Theorem List for Metamath Proof Explorer - 32801-32900   *Has distinct variable group(s)
TypeLabelDescription
Statement
 
TheoremonfrALTlem1 32801* Lemma for onfrALT 32802. (Contributed by Alan Sare, 22-Jul-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( a  C_  On  /\  a  =/=  (/) )  ->  ( ( x  e.  a  /\  ( a  i^i  x )  =  (/) )  ->  E. y  e.  a  ( a  i^i  y )  =  (/) ) )
 
TheoremonfrALT 32802 The epsilon relation is foundational on the class of ordinal numbers. onfrALT 32802 is an alternate proof of onfr 4923. onfrALTVD 33172 is the Virtual Deduction proof from which onfrALT 32802 is derived. The Virtual Deduction proof mirrors the working proof of onfr 4923 which is the main part of the proof of Theorem 7.12 of the first edition of TakeutiZaring. The proof of the corresponding Proposition 7.12 of [TakeutiZaring] p. 38 (second edition) does not contain the working proof equivalent of onfrALTVD 33172. This theorem does not rely on the Axiom of Regularity. (Contributed by Alan Sare, 22-Jul-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  _E  Fr  On
 
Theoremcsbeq2gOLD 32803 Formula-building implication rule for class substitution. Closed form of csbeq2i 3841. csbeq2gOLD 32803 is derived from the virtual deduction proof csbeq2gVD 33173. (Contributed by Alan Sare, 10-Nov-2012.) Obsolete version of csbeq2 3444 as of 11-Oct-2018. (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A  e.  V  ->  (
 A. x  B  =  C  ->  [_ A  /  x ]_ B  =  [_ A  /  x ]_ C ) )
 
Theorem19.41rg 32804 Closed form of right-to-left implication of 19.41 1920, Theorem 19.41 of [Margaris] p. 90. Derived from 19.41rgVD 33183. (Contributed by Alan Sare, 8-Feb-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A. x ( ps  ->  A. x ps )  ->  ( ( E. x ph 
 /\  ps )  ->  E. x ( ph  /\  ps )
 ) )
 
Theoremopelopab4 32805* Ordered pair membership in a class abstraction of pairs. Compare to elopab 4761. (Contributed by Alan Sare, 8-Feb-2014.) (Revised by Mario Carneiro, 6-May-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( <. u ,  v >.  e. 
 { <. x ,  y >.  |  ph }  <->  E. x E. y
 ( ( x  =  u  /\  y  =  v )  /\  ph )
 )
 
Theorem2pm13.193 32806 pm13.193 31220 for two variables. pm13.193 31220 is Theorem *13.193 in [WhiteheadRussell] p. 179. Derived from 2pm13.193VD 33184. (Contributed by Alan Sare, 8-Feb-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( ( x  =  u  /\  y  =  v )  /\  [ u  /  x ] [
 v  /  y ] ph )  <->  ( ( x  =  u  /\  y  =  v )  /\  ph )
 )
 
Theoremhbntal 32807 A closed form of hbn 1843. hbnt 1842 is another closed form of hbn 1843. (Contributed by Alan Sare, 8-Feb-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A. x ( ph  ->  A. x ph )  ->  A. x ( -.  ph  ->  A. x  -.  ph ) )
 
Theoremhbimpg 32808 A closed form of hbim 1869. Derived from hbimpgVD 33185. (Contributed by Alan Sare, 8-Feb-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( A. x ( ph  ->  A. x ph )  /\  A. x ( ps 
 ->  A. x ps )
 )  ->  A. x ( ( ph  ->  ps )  ->  A. x ( ph  ->  ps ) ) )
 
Theoremhbalg 32809 Closed form of hbal 1793. Derived from hbalgVD 33186. (Contributed by Alan Sare, 8-Feb-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A. y ( ph  ->  A. x ph )  ->  A. y ( A. y ph  ->  A. x A. y ph ) )
 
Theoremhbexg 32810 Closed form of nfex 1895. Derived from hbexgVD 33187. (Contributed by Alan Sare, 8-Feb-2014.) (Revised by Mario Carneiro, 12-Dec-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A. x A. y (
 ph  ->  A. x ph )  ->  A. x A. y
 ( E. y ph  ->  A. x E. y ph ) )
 
Theoremax6e2eq 32811* Alternate form of ax6e 1971 for non-distinct  x,  y and  u  =  v. ax6e2eq 32811 is derived from ax6e2eqVD 33188. (Contributed by Alan Sare, 25-Mar-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A. x  x  =  y  ->  ( u  =  v  ->  E. x E. y ( x  =  u  /\  y  =  v ) ) )
 
Theoremax6e2nd 32812* If at least two sets exist (dtru 4644) , then the same is true expressed in an alternate form similar to the form of ax6e 1971. ax6e2nd 32812 is derived from ax6e2ndVD 33189. (Contributed by Alan Sare, 25-Mar-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( -.  A. x  x  =  y  ->  E. x E. y ( x  =  u  /\  y  =  v ) )
 
Theoremax6e2ndeq 32813* "At least two sets exist" expressed in the form of dtru 4644 is logically equivalent to the same expressed in a form similar to ax6e 1971 if dtru 4644 is false implies  u  =  v. ax6e2ndeq 32813 is derived from ax6e2ndeqVD 33190. (Contributed by Alan Sare, 25-Mar-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( -.  A. x  x  =  y  \/  u  =  v )  <->  E. x E. y ( x  =  u  /\  y  =  v )
 )
 
Theorem2sb5nd 32814* Equivalence for double substitution 2sb5 2171 without distinct  x,  y requirement. 2sb5nd 32814 is derived from 2sb5ndVD 33191. (Contributed by Alan Sare, 30-Apr-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( -.  A. x  x  =  y  \/  u  =  v )  ->  ( [ u  /  x ] [ v  /  y ] ph  <->  E. x E. y
 ( ( x  =  u  /\  y  =  v )  /\  ph )
 ) )
 
Theorem2uasbanh 32815* Distribute the unabbreviated form of proper substitution in and out of a conjunction. 2uasbanh 32815 is derived from 2uasbanhVD 33192. (Contributed by Alan Sare, 31-May-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ch 
 <->  ( E. x E. y ( ( x  =  u  /\  y  =  v )  /\  ph )  /\  E. x E. y
 ( ( x  =  u  /\  y  =  v )  /\  ps ) ) )   =>    |-  ( E. x E. y ( ( x  =  u  /\  y  =  v )  /\  ( ph  /\  ps ) )  <-> 
 ( E. x E. y ( ( x  =  u  /\  y  =  v )  /\  ph )  /\  E. x E. y
 ( ( x  =  u  /\  y  =  v )  /\  ps ) ) )
 
Theorem2uasban 32816* Distribute the unabbreviated form of proper substitution in and out of a conjunction. (Contributed by Alan Sare, 31-May-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( E. x E. y ( ( x  =  u 
 /\  y  =  v )  /\  ( ph  /\ 
 ps ) )  <->  ( E. x E. y ( ( x  =  u  /\  y  =  v )  /\  ph )  /\  E. x E. y
 ( ( x  =  u  /\  y  =  v )  /\  ps ) ) )
 
Theoreme2ebind 32817 Absorption of an existential quantifier of a double existential quantifier of non-distinct variables. e2ebind 32817 is derived from e2ebindVD 33193. (Contributed by Alan Sare, 27-Nov-2014.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( A. x  x  =  y  ->  ( E. x E. y ph  <->  E. y ph )
 )
 
Theoremelpwgded 32818 elpwgdedVD 33198 in conventional notation. (Contributed by Alan Sare, 23-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  A  e.  _V )   &    |-  ( ps  ->  A  C_  B )   =>    |-  ( ( ph  /\  ps )  ->  A  e.  ~P B )
 
Theoremtrelded 32819 Deduction form of trel 4553. In a transitive class, the membership relation is transitive. (Contributed by Alan Sare, 3-Dec-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  Tr  A )   &    |-  ( ps  ->  B  e.  C )   &    |-  ( ch  ->  C  e.  A )   =>    |-  ( ( ph  /\  ps  /\ 
 ch )  ->  B  e.  A )
 
Theoremjaoded 32820 Deduction form of jao 512. Disjunction of antecedents. (Contributed by Alan Sare, 3-Dec-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ( ps  ->  ch ) )   &    |-  ( th  ->  ( ta  ->  ch )
 )   &    |-  ( et  ->  ( ps  \/  ta ) )   =>    |-  ( ( ph  /\  th  /\ 
 et )  ->  ch )
 
Theorem3imp31 32821 The importation inference 3imp 1190 with commutation of the first and third conjuncts of the assertion relative to the hypothesis. (Contributed by Alan Sare, 11-Sep-2016.) (Proof modification is discouraged.)
 |-  ( ph  ->  ( ps  ->  ( ch  ->  th )
 ) )   =>    |-  ( ( ch  /\  ps 
 /\  ph )  ->  th )
 
Theorem3imp21 32822 The importation inference 3imp 1190 with commutation of the first and second conjuncts of the assertion relative to the hypothesis. (Contributed by Alan Sare, 11-Sep-2016.) (Proof modification is discouraged.)
 |-  ( ph  ->  ( ps  ->  ( ch  ->  th )
 ) )   =>    |-  ( ( ps  /\  ph 
 /\  ch )  ->  th )
 
Theorembiimpa21 32823 biimpa 484 with commutation of the first and second conjuncts of the assertion. (Contributed by Alan Sare, 11-Sep-2016.)
 |-  ( ph  ->  ( ps  <->  ch ) )   =>    |-  ( ( ps 
 /\  ph )  ->  ch )
 
TheoremsbtT 32824 A substitution into a theorem remains true. sbt 2140 with the existence of no virtual hypotheses for the hypothesis expressed as the empty virtual hypothesis collection. (Contributed by Alan Sare, 4-Feb-2017.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( T.  ->  ph )   =>    |- 
 [ y  /  x ] ph
 
Theoremex3 32825 Apply ex 434 to a hypothesis with a 3-right-nested conjunction antecedent, with the antecedent of the assertion being a triple conjunction rather than a 2-right-nested conjunction. (Contributed by Alan Sare, 22-Apr-2018.)
 |-  (
 ( ( ( ph  /\ 
 ps )  /\  ch )  /\  th )  ->  ta )   =>    |-  ( ( ph  /\  ps  /\ 
 ch )  ->  ( th  ->  ta ) )
 
Theoremnot12an2impnot1 32826 If a double conjunction is false and the second conjunct is true, then the first conjunct is false. http://us.metamath.org/other/completeusersproof/not12an2impnot1vd.html is the Virtual Deduction proof verified by automatically transforming it into the Metamath proof of not12an2impnot1 32826 using completeusersproof, which is verified by the Metamath program. http://us.metamath.org/other/completeusersproof/not12an2impnot1ro.html is a form of the completed proof which preserves the Virtual Deduction proof's step numbers and their ordering. (Contributed by Alan Sare, 13-Jun-2018.)
 |-  (
 ( -.  ( ph  /\ 
 ps )  /\  ps )  ->  -.  ph )
 
21.27.5  What is Virtual Deduction?
 
Syntaxwvd1 32827 A Virtual Deduction proof in a Hilbert-style deductive system is the analog of a sequent calculus proof. A theorem is proven in a Gentzen system in order to prove more directly, which may be more intuitive and easier for some people. The analog of this proof in Metamath's Hilbert-style system is verified by the Metamath program.

Natural Deduction is a well-known proof method orignally proposed by Gentzen in 1935 and comprehensively summarized by Prawitz in his 1965 monograph "Natural deduction: a proof-theoretical study". Gentzen wished to construct "a formalism that comes as close as possible to natural reasoning". Natural deduction is a response to dissatisfaction with axiomatic proofs such as Hilbert-style axiomatic proofs, which the proofs of Metamath are. In 1926, in Poland, Lukasiewicz advocated a more natural treatment of logic. Jaskowski made the earliest attempts at defining a more natural deduction. Natural deduction in its modern form was independently proposed by Gentzen.

Sequent calculus, the chief alternative to Natural Deduction, was created by Gentzen. The following is an excerpt from Stephen Cole Kleene's seminal 1952 book "Introduction to Metamathematics", which contains the first formulation of sequent calculus in the modern style. Kleene states on page 440:

. . . the proof (of Gentzen's Hauptsatz) breaks down into a list of cases, each of which is simple to handle. . . . Gentzen's normal form for proofs in the predicate calculus requires a different classification of the deductive steps than is given by the postulates of the formal system of predicate calculus of Chapter IV (Section 19). The implication symbol  -> (the Metamath symbol for implication has been substituted here for the symbol used by Kleene) has to be separated in its role of mediating inferences from its role as a component symbol of the formula being proved. In the former role it will be replaced by a new formal symbol 
->.. (read "gives" or "entails"), to which properties will be assigned similar to those of the informal symbol  |- in our former derived rules.

Gentzen's classification of the deductive operations is made explicit by setting up a new formal system of the predicate calculus. The formal system of propositional and predicate calculus studied previously (Chapters IV ff.) we call now a "Hilbert-type system", and denote by H. Precisely, H denotes any one or a particular one of several systems, according to whether we are considering propositional calculus or predicate calculus, in the classical or the intuitionistic version (Section 23), and according to the sense in which we are using "term" and "formula" (Sections 117,25,31,37,72-76). The same respective choices will apply to the "Gentzen-type system G1" which we introduce now and the G2, G3 and G3a later.

The transformation or deductive rules of G1 will apply to objects which are not formulas of the system H, but are built from them by an additional formation rule, so we use a new term "sequent" for these objects. (Gentzen says "Sequenz", which we translate as "sequent", because we have already used "sequence" for any succession of objects, where the German is "Folge".) A sequent is a formal expression of the form  ph, . . . ,  ps  ->..  ch, . . . ,  th where  ph , . . . ,  ps and  ch, . . . ,  th are seqences of a finite number of 0 or more formulas (substituting Metamath notation for Kleene's notation). The part  ph, . . . ,  ps is the antecedent, and  ch, . . . ,  th the succedent of the sequent  ph, . . . ,  ps  ->..  ch, . . . ,  th.

When the antecedent and the succedent each have a finite number of 1 or more formulas, the sequent 
ph, . . . ,  ps  ->..  ch, . . .  th has the same interpretation for G1 as the formula  ( ( ph  /\. . .  /\  ps )  ->  ( ch  \/. . .  \/  th ) ) for H. The interpretation extends to the case of an antecedent of 0 formulas by regarding  ( ph  /\. . .  /\ 
ps ) for 0 formulas (the "empty conjunction") as true and 
( ch  \/. . .  \/  th ) for 0 formulas (the "empty disjunction") as false.

. . . As in Chapter V, we use Greek capitals . . . to stand for finite sequences of zero or more formulas, but now also as antecedent (succedent), or parts of antecedent (succedent), with separating formal commas included. . . . (End of Kleene excerpt)

In chapter V entitled "Formal Deduction" Kleene states, on page 86:

Section 20. Formal deduction. Formal proofs of even quite elementary theorems tend to be long. As a price for having analyzed logical deduction into simple steps, more of those steps have to be used.

The purpose of formalizing a theory is to get an explicit definition of what constitutes proof in the theory. Having achieved this, there is no need always to appeal directly to the definition. The labor required to establish the formal provability of formulas can be greatly lessened by using metamathematical theorems concerning the existence of formal proofs. If the demonstrations of those theorems do have the finitary character which metamathematics is supposed to have, the demonstrations will indicate, at least implicitly, methods for obtaining the formal proofs. The use of the metamathematical theorems then amounts to abbreviation, often of very great extent, in the presentation of formal proofs.

The simpler of such metamathematical theorems we shall call derived rules, since they express principles which can be said to be derived from the postulated rules by showing that the use of them as additional methods of inference does not increase the class of provable formulas. We shall seek by means of derived rules to bring the methods for establishing the facts of formal provability as close as possible to the informal methods of the theory which is being formalized.

In setting up the formal system, proof was given the simplest possible structure, consisting of a single sequence of formulas. Some of our derived rules, called "direct rules", will serve to abbreviate for us whole segments of such a sequence; we can then, so to speak, use these segments as prefabricated units in building proofs.

But also, in mathematical practice, proofs are common which have a more complicated structure, employing "subsidiary deduction", i.e. deduction under assumptions for the sake of the argument, which assumptions are subsequently discharged. For example, subsidiary deduction is used in a proof by reductio ad absurdum, and less obtrusively when we place the hypothesis of a theorem on a par with proved propositions to deduce the conclusion. Other derived rules, called "subsidiary deduction rules", will give us this kind of procedure.

We now introduce, by a metamathematical definition, the notion of "formal deducibility under assumptions". Given a list  ph, . . .  ps of  0 or more (occurrences of) formulas, a finite sequence of one or more (occurrences of) formulas is called a (formal) deduction from the assumption formulas 
ph, . . .  ps, if each formula of the sequence is either one of the formulas  ph, . . .  ps, or an axiom, or an immediate consequence of preceding formulas of a sequence. A deduction is said to be deducible from the assumption formulas (in symbols,  ph,. . . . ,.  ps |-  ch), and is called the conclusion (or endformula) of the deduction. (The symbol  |- may be read "yields".) (End of Kleene excerpt)

Gentzen's normal form is a certain direct fashion for proofs and deductions. His sequent calculus, formulated in the modern style by Kleene, is the classical system G1. In this system, the new formal symbol  ->.. has properties similar to the informal symbol  |- of Kleene's above language of formal deducibility under assumptions.

Kleene states on page 440:

. . . This leads us to inquire whether there may not be a theorem about the predicate calculus asserting that, if a formula is provable (or deducible from other formulas), it is provable (or deducible) in a certain direct fashion; in other words, a theorem giving a normal form for proofs and deductions, the proofs and deduction in normal form being in some sense direct. (End of Kleene excerpt)

There is such a theorem, which was proven by Kleene.

Formal proofs in H of even quite elementary theorems tend to be long. As a price for having analyzed logical deduction into simple steps, more of those steps have to be used. The proofs of Metamath are fully detailed formal proofs. We wish to have a means of writing rigorously verifiable mathematical proofs in a more direct fashion. Natural Deduction is a system for proving theorems and deductions in a more direct fashion. However, Natural Deduction is not compatible for use with Metamath, which uses a Hilbert-type system. Instead, Kleene's classical system G1 may be used for proving Metamath deductions and theorems in a more direct fashion.

The system of Metamath is an H system, not a Gentzen system. Therefore, proofs in Kleene's classical system G1 ("G1") cannot be included in Metamath's system H, which we shall henceforth call "system H" or "H". However, we may translate proofs in G1 into proofs in H.

By Kleene's THEOREM 47 (page 446)

if  |-  ->..  ph in G1 then  |-  ph in H

By Kleene's COROLLARY of THEOREM 47 (page 448)

if  |-  ph  ->..  ps in G1 then  |-  (. ph  ->.  ps ). in H
if  |-  ph ,. ps  ->..  ch in G1 then  |-  (. (. ph ,. ps ).  ->.  ch ). in H
if  |-  ph ,. ps ,. ch  ->..  th in G1 then  |-  (. (. ph ,. ps ,. ch ).  ->.  th ). in H

 ->. denotes the same connective denoted by  ->. " , " , in the context of Virtual Deduction, denotes the same connective denoted by  /\. This Virtual Deduction notation is specified by the following set.mm definitions:

df-vd1 32828  |-  ( (. ph  ->.  ps ).  <->  ( ph  ->  ps ) )
dfvd2an 32840  |-  ( (. (. ph ,. ps ).  ->.  ch ).  <->  ( ( ph  /\  ps )  ->  ch ) )
dfvd3an 32852  |-  ( (. (. ph ,. ps ,. ch ).  ->.  th ).  <->  ( ( ph  /\  ps  /\  ch )  ->  th ) )

 ->. replaces 
->.. in the analog in H of a sequent in G1 having a nonempty antecedent. If  ->. occurs as the outermost connective denoted by 
->. or  -> and occurs exactly once, we call the analog in H of a sequent in G1 a "virtual deduction" because the corresponding  ->.. of the sequent is assigned properties similar to  |-.

While sequent calculus proofs (proofs in G1) may have as steps sequents with 0, 1, or more formulas in the succedent, we shall only prove in G1 using sequents with exactly 1 formula in the succedent.

The User proves in G1 in order to obtain the benefits of more direct proving using sequent calculus, then translates the proof in G1 into a proof in H. The reference theorems and deductions to be used for proving in G1 are translations of theorems and deductions in set.mm.

Each theorem  |-  ph in set.mm corresponds to the theorem  |-  ->..  ph in G1. Deductions in G1 corresponding to deductions in H are similarly determined. Theorems in H with one or more occurrences of either  ->. or  -> may also be translated into theorems in G1 for by replacing the outermost occurrence of  ->. or  -> of the theorem in H with  ->... Deductions in H may be translated into deductions in G1 in a similar manner. The only theorems and deductions in H useful for proving in G1 for the purpose of obtaining proofs in H are those in which, for each hypothesis or assertion, there are 0 or 1 occurrences of  ->. and it is the outermost occurrence of  ->. or  ->. Kleene's THEOREM 46 and its COROLLARY 2 are used for translating from H to G1. By Kleene's THEOREM 46 (page 445)

if  |-  ph in H then  |-  ->..  ph in G1

By Kleene's COROLLARY 2 of THEOREM 46 (page 446)

if  |-  (. ph  ->.  ps ). in H then  |-  ph  ->..  ps in G1
if  |-  (. (. ph ,. ps ).  ->.  ch ). in H then  |-  ph ,. ps  ->..  ch in G1
if  |-  (. (. ph ,. ps ,. ch ).  ->.  th ). in H then  |-  ph ,. ps ,. ch  ->..  th in G1

To prove in H, the User simply proves in G1 and translates each G1-proof step into a H-proof step. The translation is trivial and immediate. The proof in H is in Virtual Deduction notation. It is a working proof in the sense that, if it has no errors, each theorem and deduction of the proof is true, but may or may not, after being translated into conventional notation, unify with any theorem or deduction scheme in set.mm. Each theorem or deduction scheme in set.mm has a particular form. The working proof written by the User (the "User's Proof" or "Virtual Deduction Proof") may contain theorems and deductions which would unify with a variant of a theorem or deduction scheme in set.mm, but not with any particular form of that theorem or deduction scheme in set.mm.

The computer program completeusersproof.c may be applied to a Virtual Deduction proof to automatically add steps to the proof ("technical steps") which, if possible, transforms the form of a theorem or deduction of the Virtual Deduction proof not unifiable with a theorem or deduction scheme in set.mm into a variant form which is. For theorems and deductions of the Virtual Deduction proof which are completable in this way, completeusersproof saves the User the extra work involved in satisfying the constraint that the theorem or deduction is in a form which unifies with a theorem or deduction scheme in set.mm. mmj2, which is invoked by completeusersproof, automatically finds one of the reference theorems or deductions in set.mm which unifies with each theorem and deduction in the proof satisfying this constraint and labels the theorem or the assertion step of the deduction.

The analogs in H of the postulates of G1 are the set.mm postulates. The postulates in G1 corresponding to the Metamath postulates are not the classical system G1 postulates of Kleene (pages 442 and 443). set.mm has the predicate calculus postulates and other posulates. The Kleene classical system G1 postulates correspond to predicate calculus postulates which differ from the Metamath system G1 postulates corresponding to the predicate calculus postulates of Metamath's system H. Metamath's predicate calculus G1 postulates are presumably deducible from the Kleene classical G1 postulates and the Kleene classical G1 postulates are deducible from Metamath's G1 postulates. It should be recognized that, because of the different postulates, the classical G1 system corresponding to Metamath's system H is not identical to Kleene's classical system G1.

Why not create a separate database (setg.mm) of proofs in G1, avoiding the need to translate from H to G1 and from G1 back to H? The translations are trivial. Sequents make the language more complex than is necessary. More direct proving using sequent calculus may be done as a means towards the end of constructing proofs in H. Then, the language may be kept as simple as possible. A system G1 database would be redundant because it would duplicate the information contained in the corresponding system H database.

For earlier proofs, each "User's Proof" in the web page description of a Virtual Deduction proof in set.mm is the analog in H of the User's working proof in G1. The User's Proof is automatically completed by completeusersproof.cmd (superseded by completeusersproof.c in September of 2016). The completed proof is the Virtual Deduction proof, which is the analog in H of the corresponding fully detailed proof in G1. The completed Virtual Deduction proof of these earlier proofs may be automatically translated into a conventional Metamath proof.

The input for completeusersproof.c is a Virtual Deduction proof. Unlike completeusersproof.cmd, the completed proof is in conventional notation. completeusersproof.c eliminates the virtual deduction notation of the Virtual Deduction proof after utilizing the information it provides.

Applying mmj2's unify command is essential to completeusersproof. The mmj2 program is invoked within the completeusersproof.c function mmj2Unify(). The original mmj2 program was written by Mel L. O'Cat. Mario Carneiro has enhanced it. mmj2Unify() is called multiple times during the execution of completeusersproof.

A Virtual Deduction proof is a Metamath-specific version of a Natural Deduction Proof. In order for mmj2 to complete a Virtual Deduction proof it is necessary that each theorem or deduction of the proof is in a form which unifies with a theorem or deduction scheme in set.mm. completeusersproof weakens this constraint.

The User may write a Virtual Deduction proof and automatically transform it into a complete Metamath proof using the completeusersproof tool. The completed proof has been checked by the Metamath program. The task of writing a complete Metamath proof is reduced to writing what is essentially a Natural Deduction Proof.

The completeusersproof program and all associated files necessary to use it may be downloaded from the Metamath web site. All syntax definitions, theorems, and deductions necessary to create Virtual Deduction proofs are contained in set.mm. Examples of Virtual Deduction proofs in mmj2 Proof Worksheet .txt format are included in the completeusersproof download.

http://us.metamath.org/other/completeusersproof/suctrvd.html, http://us.metamath.org/other/completeusersproof/sineq0altvd.html, http://us.metamath.org/other/completeusersproof/iunconlem2vd.html, http://us.metamath.org/other/completeusersproof/isosctrlem1altvd.html, and http://us.metamath.org/other/completeusersproof/chordthmaltvd.html are examples of Virtual Deduction proofs.

Generally, proving using Virtual Deduction and completeusersproof reduces the amount of Metamath-specific knowledge required by the User. Often, no knowledge of the specific theorems and deductions in set.mm is required to write some of the subproofs of a Virtual Deduction proof. Often, no knowledge of the Metamath-specific names of reference theorems and deductions in set.mm is required for writing some of the subproofs of a User's Proof. Often, the User may write subproofs of a proof using theorems or deductions commonly used in mathematics and correctly assume that some form of each is contained in set.mm and that completeusersproof will automatically generate the technical steps necessary to utilize them to complete the subproofs. Often, the fraction of the work which may be considered tedious is reduced and the total amount of work is reduced.

 wff  (.
 ph 
 ->.  ps ).
 
21.27.6  Virtual Deduction Theorems
 
Definitiondf-vd1 32828 Definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011.) (New usage is discouraged.)
 |-  ( (. ph  ->.  ps ).  <->  ( ph  ->  ps ) )
 
Theoremin1 32829 Inference form of df-vd1 32828. Virtual deduction introduction rule of converting the virtual hypothesis of a 1-virtual hypothesis virtual deduction into an antecedent. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   =>    |-  ( ph  ->  ps )
 
Theoremiin1 32830 in1 32829 without virtual deductions. (Contributed by Alan Sare, 23-Jul-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ps )   =>    |-  ( ph  ->  ps )
 
Theoremdfvd1ir 32831 Inference form of df-vd1 32828 with the virtual deduction as the assertion. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ps )   =>    |- 
 (. ph  ->.  ps ).
 
Theoremidn1 32832 Virtual deduction identity rule which is id 22 with virtual deduction symbols. (Contributed by Alan Sare, 24-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ph ).
 
Theoremdfvd1imp 32833 Left-to-right part of definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( (. ph  ->.  ps ).  ->  ( ph  ->  ps ) )
 
Theoremdfvd1impr 32834 Right-to-left part of definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( ph  ->  ps )  ->  (. ph  ->.  ps ). )
 
Syntaxwvd2 32835 Syntax for a 2-hypothesis virtual deduction. (New usage is discouraged.)
 wff  (.
 ph ,. ps  ->.  ch ).
 
Definitiondf-vd2 32836 Definition of a 2-hypothesis virtual deduction. (Contributed by Alan Sare, 14-Nov-2011.) (New usage is discouraged.)
 |-  ( (. ph ,. ps  ->.  ch ).  <->  ( ( ph  /\ 
 ps )  ->  ch )
 )
 
Theoremdfvd2 32837 Definition of a 2-hypothesis virtual deduction. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( (. ph ,. ps  ->.  ch ).  <->  ( ph  ->  ( ps  ->  ch )
 ) )
 
Syntaxwvhc2 32838 Syntax for a 2-element virtual hypotheses collection. (Contributed by Alan Sare, 23-Apr-2015.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ).
 
Definitiondf-vhc2 32839 Definition of a 2-element virtual hypotheses collection. (Contributed by Alan Sare, 23-Apr-2015.) (New usage is discouraged.)
 |-  ( (. ph ,. ps ).  <->  (
 ph  /\  ps )
 )
 
Theoremdfvd2an 32840 Definition of a 2-hypothesis virtual deduction in vd conjunction form. (Contributed by Alan Sare, 23-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( (. (. ph ,. ps ).  ->.  ch ).  <->  ( ( ph  /\ 
 ps )  ->  ch )
 )
 
Theoremdfvd2ani 32841 Inference form of dfvd2an 32840. (Contributed by Alan Sare, 23-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. (. ph
 ,. ps ).  ->.  ch ).   =>    |-  ( ( ph  /\ 
 ps )  ->  ch )
 
Theoremdfvd2anir 32842 Right-to-left inference form of dfvd2an 32840. (Contributed by Alan Sare, 23-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( ph  /\  ps )  ->  ch )   =>    |- 
 (. (. ph ,. ps ).  ->.  ch ).
 
Theoremdfvd2i 32843 Inference form of dfvd2 32837. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   =>    |-  ( ph  ->  ( ps  ->  ch ) )
 
Theoremdfvd2ir 32844 Right-to-left inference form of dfvd2 32837. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ( ps  ->  ch ) )   =>    |- 
 (. ph ,. ps  ->.  ch ).
 
Syntaxwvd3 32845 Syntax for a 3-hypothesis virtual deduction. (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch  ->.  th
 ).
 
Syntaxwvhc3 32846 Syntax for a 3-element virtual hypotheses collection. (Contributed by Alan Sare, 13-Jun-2015.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ).
 
Definitiondf-vhc3 32847 Definition of a 3-element virtual hypotheses collection. (Contributed by Alan Sare, 13-Jun-2015.) (New usage is discouraged.)
 |-  ( (. ph ,. ps ,. ch ).  <->  ( ph  /\  ps  /\ 
 ch ) )
 
Definitiondf-vd3 32848 Definition of a 3-hypothesis virtual deduction. (Contributed by Alan Sare, 14-Nov-2011.) (New usage is discouraged.)
 |-  ( (. ph ,. ps ,. ch  ->. 
 th ).  <->  ( ( ph  /\ 
 ps  /\  ch )  ->  th ) )
 
Theoremdfvd3 32849 Definition of a 3-hypothesis virtual deduction. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( (. ph ,. ps ,. ch  ->. 
 th ).  <->  ( ph  ->  ( ps  ->  ( ch  ->  th ) ) ) )
 
Theoremdfvd3i 32850 Inference form of dfvd3 32849. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps ,. ch  ->.  th ).   =>    |-  ( ph  ->  ( ps  ->  ( ch  ->  th ) ) )
 
Theoremdfvd3ir 32851 Right-to-left inference form of dfvd3 32849. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ( ps  ->  ( ch  ->  th )
 ) )   =>    |- 
 (. ph ,. ps ,. ch  ->. 
 th ).
 
Theoremdfvd3an 32852 Definition of a 3-hypothesis virtual deduction in vd conjunction form. (Contributed by Alan Sare, 13-Jun-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( (. (. ph ,. ps ,. ch ).  ->.  th ).  <->  ( ( ph  /\ 
 ps  /\  ch )  ->  th ) )
 
Theoremdfvd3ani 32853 Inference form of dfvd3an 32852. (Contributed by Alan Sare, 13-Jun-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. (. ph
 ,. ps ,. ch ).  ->.  th
 ).   =>    |-  ( ( ph  /\  ps  /\ 
 ch )  ->  th )
 
Theoremdfvd3anir 32854 Right-to-left inference form of dfvd3an 32852. (Contributed by Alan Sare, 13-Jun-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( ph  /\  ps  /\  ch )  ->  th )   =>    |-  (. (. ph
 ,. ps ,. ch ).  ->.  th
 ).
 
Syntaxwvhc4 32855 Syntax for a 4-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ).
 
Syntaxwvhc5 32856 Syntax for a 5-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ).
 
Syntaxwvhc6 32857 Syntax for a 6-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ).
 
Syntaxwvhc7 32858 Syntax for a 7-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ,. ze ).
 
Syntaxwvhc8 32859 Syntax for an 8-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ,. ze ,. si ).
 
Syntaxwvhc9 32860 Syntax for a 9-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ,. ze ,. si ,. rh ).
 
Syntaxwvhc10 32861 Syntax for a 10-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ,. ze ,. si ,. rh ,. mu ).
 
Syntaxwvhc11 32862 Syntax for an 11-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ,. ze ,. si ,. rh ,. mu ,. la
 ).
 
Syntaxwvhc12 32863 Syntax for a 12-element virtual hypotheses collection. (Contributed by Alan Sare, 17-Oct-2017.) (New usage is discouraged.)
 wff  (.
 ph ,. ps ,. ch ,. th ,. ta ,. et ,. ze ,. si ,. rh ,. mu ,. la
 ,. ka ).
 
Theoremvd01 32864 A virtual hypothesis virtually infers a theorem. (Contributed by Alan Sare, 14-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ph   =>    |- 
 (. ps  ->.  ph ).
 
Theoremvd02 32865 Two virtual hypotheses virtually infer a theorem. (Contributed by Alan Sare, 14-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ph   =>    |- 
 (. ps ,. ch  ->.  ph ).
 
Theoremvd03 32866 A theorem is virtually inferred by the 3 virtual hypotheses. (Contributed by Alan Sare, 12-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ph   =>    |- 
 (. ps ,. ch ,. th  ->. 
 ph ).
 
Theoremvd12 32867 A virtual deduction with 1 virtual hypothesis virtually inferring a virtual conclusion infers that the same conclusion is virtually inferred by the same virtual hypothesis and an additional hypothesis. (Contributed by Alan Sare, 12-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   =>    |- 
 (. ph ,. ch  ->.  ps ).
 
Theoremvd13 32868 A virtual deduction with 1 virtual hypothesis virtually inferring a virtual conclusion infers that the same conclusion is virtually inferred by the same virtual hypothesis and a two additional hypotheses. (Contributed by Alan Sare, 12-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   =>    |- 
 (. ph ,. ch ,. th  ->.  ps ).
 
Theoremvd23 32869 A virtual deduction with 2 virtual hypotheses virtually inferring a virtual conclusion infers that the same conclusion is virtually inferred by the same 2 virtual hypotheses and a third hypothesis. (Contributed by Alan Sare, 12-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   =>    |- 
 (. ph ,. ps ,. th  ->.  ch ).
 
Theoremdfvd2imp 32870 The virtual deduction form of a 2-antecedent nested implication implies the 2-antecedent nested implication. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( (. ph ,. ps  ->.  ch ).  ->  (
 ph  ->  ( ps  ->  ch ) ) )
 
Theoremdfvd2impr 32871 A 2-antecedent nested implication implies its virtual deduction form. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  (. ph ,. ps  ->.  ch ). )
 
Theoremin2 32872 The virtual deduction introduction rule of converting the end virtual hypothesis of 2 virtual hypotheses into an antecedent. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   =>    |- 
 (. ph  ->.  ( ps  ->  ch ) ).
 
Theoremint2 32873 The virtual deduction introduction rule of converting the end virtual hypothesis of 2 virtual hypotheses into an antecedent. Conventional form of int2 32873 is ex 434. (Contributed by Alan Sare, 23-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. (. ph
 ,. ps ).  ->.  ch ).   =>    |-  (. ph  ->.  ( ps  ->  ch ) ).
 
Theoremiin2 32874 in2 32872 without virtual deductions. (Contributed by Alan Sare, 20-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ( ps  ->  ch ) )   =>    |-  ( ph  ->  ( ps  ->  ch ) )
 
Theoremin2an 32875 The virtual deduction introduction rule converting the second conjunct of the second virtual hypothesis into the antecedent of the conclusion. expd 436 is the non-virtual deduction form of in2an 32875. (Contributed by Alan Sare, 30-Jun-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ( ps  /\  ch ) 
 ->.  th ).   =>    |- 
 (. ph ,. ps  ->.  ( ch  ->  th ) ).
 
Theoremin3 32876 The virtual deduction introduction rule of converting the end virtual hypothesis of 3 virtual hypotheses into an antecedent. (Contributed by Alan Sare, 12-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps ,. ch  ->.  th ).   =>    |-  (. ph ,. ps  ->.  ( ch  ->  th ) ).
 
Theoremiin3 32877 in3 32876 without virtual deduction connectives. Special theorem needed for the Virtual Deduction translation tool. (Contributed by Alan Sare, 23-Jul-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ( ps  ->  ( ch  ->  th )
 ) )   =>    |-  ( ph  ->  ( ps  ->  ( ch  ->  th ) ) )
 
Theoremin3an 32878 The virtual deduction introduction rule converting the second conjunct of the third virtual hypothesis into the antecedent of the conclusion. exp4a 606 is the non-virtual deduction form of in3an 32878. (Contributed by Alan Sare, 25-Jun-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps ,. ( ch 
 /\  th )  ->.  ta ).   =>    |-  (. ph ,. ps ,. ch  ->.  ( th  ->  ta ) ).
 
Theoremint3 32879 The virtual deduction introduction rule of converting the end virtual hypothesis of 3 virtual hypotheses into an antecedent. Conventional form of int3 32879 is 3expia 1198. (Contributed by Alan Sare, 13-Jun-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. (. ph
 ,. ps ,. ch ).  ->.  th
 ).   =>    |- 
 (. (. ph ,. ps ).  ->.  ( ch  ->  th ) ).
 
Theoremidn2 32880 Virtual deduction identity rule which is idd 24 with virtual deduction symbols. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ps ).
 
Theoremiden2 32881 Virtual deduction identity rule. simpr 461 in conjunction form Virtual Deduction notation. (Contributed by Alan Sare, 5-Sep-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. (. ph
 ,. ps ).  ->.  ps ).
 
Theoremidn3 32882 Virtual deduction identity rule for 3 virtual hypotheses. (Contributed by Alan Sare, 11-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps ,. ch  ->.  ch ).
 
Theoremgen11 32883* Virtual deduction generalizing rule for 1 quantifying variable and 1 virtual hypothesis. alrimiv 1695 is gen11 32883 without virtual deductions. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   =>    |- 
 (. ph  ->.  A. x ps ).
 
Theoremgen11nv 32884 Virtual deduction generalizing rule for 1 quantifying variable and 1 virtual hypothesis without distinct variables. alrimih 1622 is gen11nv 32884 without virtual deductions. (Contributed by Alan Sare, 12-Dec-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  A. x ph )   &    |-  (. ph  ->.  ps
 ).   =>    |- 
 (. ph  ->.  A. x ps ).
 
Theoremgen12 32885* Virtual deduction generalizing rule for 2 quantifying variables and 1 virtual hypothesis. gen12 32885 is alrimivv 1696 with virtual deductions. (Contributed by Alan Sare, 2-May-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   =>    |- 
 (. ph  ->.  A. x A. y ps ).
 
Theoremgen21 32886* Virtual deduction generalizing rule for 1 quantifying variables and 2 virtual hypothesis. gen21 32886 is alrimdv 1697 with virtual deductions. (Contributed by Alan Sare, 25-Jul-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   =>    |- 
 (. ph ,. ps  ->.  A. x ch ).
 
Theoremgen21nv 32887 Virtual deduction form of alrimdh 1649. (Contributed by Alan Sare, 31-Dec-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  A. x ph )   &    |-  ( ps  ->  A. x ps )   &    |-  (. ph ,. ps  ->.  ch ).   =>    |- 
 (. ph ,. ps  ->.  A. x ch ).
 
Theoremgen31 32888* Virtual deduction generalizing rule for 1 quantifying variable and 3 virtual hypothesis. gen31 32888 is ggen31 32798 with virtual deductions. (Contributed by Alan Sare, 22-Jun-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps ,. ch  ->.  th ).   =>    |-  (. ph ,. ps ,. ch  ->.  A. x th ).
 
Theoremgen22 32889* Virtual deduction generalizing rule for 2 quantifying variables and 2 virtual hypothesis. (Contributed by Alan Sare, 25-Jul-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   =>    |- 
 (. ph ,. ps  ->.  A. x A. y ch ).
 
Theoremggen22 32890* gen22 32889 without virtual deductions. (Contributed by Alan Sare, 25-Jul-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ph  ->  ( ps  ->  ch ) )   =>    |-  ( ph  ->  ( ps  ->  A. x A. y ch ) )
 
Theoremexinst 32891 Existential Instantiation. Virtual deduction form of exlimexi 32774. (Contributed by Alan Sare, 21-Apr-2013.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  ( ps  ->  A. x ps )   &    |-  (. E. x ph ,. ph  ->.  ps ).   =>    |-  ( E. x ph 
 ->  ps )
 
Theoremexinst01 32892 Existential Instantiation. Virtual Deduction rule corresponding to a special case of the Natural Deduction Sequent Calculus rule called Rule C in [Margaris] p. 79 and E  E. in Table 1 on page 4 of the paper "Extracting information from intermediate T-systems" (2000) presented at IMLA99 by Mauro Ferrari, Camillo Fiorentini, and Pierangelo Miglioli. (Contributed by Alan Sare, 21-Apr-2013.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  E. x ps   &    |- 
 (. ph ,. ps  ->.  ch ).   &    |-  ( ph  ->  A. x ph )   &    |-  ( ch  ->  A. x ch )   =>    |-  (. ph  ->.  ch
 ).
 
Theoremexinst11 32893 Existential Instantiation. Virtual Deduction rule corresponding to a special case of the Natural Deduction Sequent Calculus rule called Rule C in [Margaris] p. 79 and E  E. in Table 1 on page 4 of the paper "Extracting information from intermediate T-systems" (2000) presented at IMLA99 by Mauro Ferrari, Camillo Fiorentini, and Pierangelo Miglioli. (Contributed by Alan Sare, 21-Apr-2013.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  E. x ps ).   &    |-  (. ph ,. ps  ->.  ch ).   &    |-  ( ph  ->  A. x ph )   &    |-  ( ch  ->  A. x ch )   =>    |-  (. ph  ->.  ch
 ).
 
Theoreme1a 32894 A Virtual deduction elimination rule. syl 16 is e1a 32894 without virtual deductions. (Contributed by Alan Sare, 11-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   &    |-  ( ps  ->  ch )   =>    |-  (. ph  ->.  ch
 ).
 
Theoremel1 32895 A Virtual deduction elimination rule. syl 16 is el1 32895 without virtual deductions. (Contributed by Alan Sare, 23-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   &    |-  ( ps  ->  ch )   =>    |-  (. ph  ->.  ch
 ).
 
Theoreme1bi 32896 Biconditional form of e1a 32894. sylib 196 is e1bi 32896 without virtual deductions. (Contributed by Alan Sare, 15-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   &    |-  ( ps  <->  ch )   =>    |- 
 (. ph  ->.  ch ).
 
Theoreme1bir 32897 Right biconditional form of e1a 32894. sylibr 212 is e1bir 32897 without virtual deductions. (Contributed by Alan Sare, 24-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph  ->.  ps
 ).   &    |-  ( ch  <->  ps )   =>    |- 
 (. ph  ->.  ch ).
 
Theoreme2 32898 A virtual deduction elimination rule. syl6 33 is e2 32898 without virtual deductions. (Contributed by Alan Sare, 21-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   &    |-  ( ch  ->  th )   =>    |- 
 (. ph ,. ps  ->.  th ).
 
Theoreme2bi 32899 Biconditional form of e2 32898. syl6ib 226 is e2bi 32899 without virtual deductions. (Contributed by Alan Sare, 10-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   &    |-  ( ch  <->  th )   =>    |- 
 (. ph ,. ps  ->.  th ).
 
Theoreme2bir 32900 Right biconditional form of e2 32898. syl6ibr 227 is e2bir 32900 without virtual deductions. (Contributed by Alan Sare, 29-Apr-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
 |-  (. ph ,. ps  ->.  ch ).   &    |-  ( th  <->  ch )   =>    |- 
 (. ph ,. ps  ->.  th ).
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