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Theorem ex-natded5.2 20649
Description: Theorem 5.2 of [Laboreo] p. 15, translated line by line using the interpretation of natural deduction in Metamath. For information about ND and Metamath, see the page on Deduction Form and Natural Deduction in Metamath Proof Explorer. The original proof, which uses Fitch style, was written as follows:
#MPE#ND Expression MPE TranslationND Rationale MPE Rationale
15  ( ( ps  /\  ch )  ->  th )  ( ph  ->  ( ( ps  /\  ch )  ->  th ) ) Given $e.
22  ( ch  ->  ps )  ( ph  ->  ( ch  ->  ps ) ) Given $e.
31  ch  ( ph  ->  ch ) Given $e.
43  ps  ( ph  ->  ps )  ->E 2,3 mpd 16, the MPE equivalent of  ->E, 1,2
54  ( ps  /\  ch )  ( ph  ->  ( ps  /\  ch ) )  /\I 4,3 jca 520, the MPE equivalent of  /\I, 3,1
66  th  ( ph  ->  th )  ->E 1,5 mpd 16, the MPE equivalent of  ->E, 4,5

The original used Latin letters for predicates; we have replaced them with Greek letters to follow Metamath naming conventions and so that it is easier to follow the Metamath translation. The Metamath line-for-line translation of this natural deduction approach precedes every line with an antecedent including  ph and uses the Metamath equivalents of the natural deduction rules. Below is the final metamath proof (which reorders some steps). A much more efficient proof, using more of Metamath and MPE's capabilities, is shown in ex-natded5.2-2 20650. A proof without context is shown in ex-natded5.2i 20651. (Proof modification is discouraged.) (Contributed by Mario Carneiro, 9-Feb-2017.)

Hypotheses
Ref Expression
ex-natded5.2.1  |-  ( ph  ->  ( ( ps  /\  ch )  ->  th )
)
ex-natded5.2.2  |-  ( ph  ->  ( ch  ->  ps ) )
ex-natded5.2.3  |-  ( ph  ->  ch )
Assertion
Ref Expression
ex-natded5.2  |-  ( ph  ->  th )

Proof of Theorem ex-natded5.2
StepHypRef Expression
1 ex-natded5.2.3 . . . 4  |-  ( ph  ->  ch )
2 ex-natded5.2.2 . . . 4  |-  ( ph  ->  ( ch  ->  ps ) )
31, 2mpd 16 . . 3  |-  ( ph  ->  ps )
43, 1jca 520 . 2  |-  ( ph  ->  ( ps  /\  ch ) )
5 ex-natded5.2.1 . 2  |-  ( ph  ->  ( ( ps  /\  ch )  ->  th )
)
64, 5mpd 16 1  |-  ( ph  ->  th )
Colors of variables: wff set class
Syntax hints:    -> wi 6    /\ wa 360
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10
This theorem depends on definitions:  df-bi 179  df-an 362
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