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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | syl22anc 1101 | Syllogism combined with contraction. |
| Theorem | syl13anc 1102 | Syllogism combined with contraction. |
| Theorem | syl31anc 1103 | Syllogism combined with contraction. |
| Theorem | syl112anc 1104 | Syllogism combined with contraction. |
| Theorem | syl121anc 1105 | Syllogism combined with contraction. |
| Theorem | syl211anc 1106 | Syllogism combined with contraction. |
| Theorem | syl23anc 1107 | Syllogism combined with contraction. |
| Theorem | syl32anc 1108 | Syllogism combined with contraction. |
| Theorem | syl122anc 1109 | Syllogism combined with contraction. |
| Theorem | syl212anc 1110 | Syllogism combined with contraction. |
| Theorem | syl221anc 1111 | Syllogism combined with contraction. |
| Theorem | syl113anc 1112 | Syllogism combined with contraction. |
| Theorem | syl131anc 1113 | Syllogism combined with contraction. |
| Theorem | syl311anc 1114 | Syllogism combined with contraction. |
| Theorem | syl33anc 1115 | Syllogism combined with contraction. |
| Theorem | syl222anc 1116 | Syllogism combined with contraction. |
| Theorem | syl123anc 1117 | Syllogism combined with contraction. |
| Theorem | syl213anc 1118 | Syllogism combined with contraction. |
| Theorem | syl231anc 1119 | Syllogism combined with contraction. |
| Theorem | syl133anc 1120 | Syllogism combined with contraction. |
| Theorem | syl313anc 1121 | Syllogism combined with contraction. |
| Theorem | syl331anc 1122 | Syllogism combined with contraction. |
| Theorem | syl223anc 1123 | Syllogism combined with contraction. |
| Theorem | syl232anc 1124 | Syllogism combined with contraction. |
| Theorem | syl322anc 1125 | Syllogism combined with contraction. |
| Theorem | syl233anc 1126 | Syllogism combined with contraction. |
| Theorem | syl323anc 1127 | Syllogism combined with contraction. |
| Theorem | syl332anc 1128 | Syllogism combined with contraction. |
| Theorem | syl333anc 1129 | A syllogism inference combined with contraction. |
| Theorem | syl3an1 1130 | A syllogism inference. |
| Theorem | syl3an2 1131 | A syllogism inference. |
| Theorem | syl3an3 1132 | A syllogism inference. |
| Theorem | syl3an1b 1133 | A syllogism inference. |
| Theorem | syl3an2b 1134 | A syllogism inference. |
| Theorem | syl3an3b 1135 | A syllogism inference. |
| Theorem | syl3an1br 1136 | A syllogism inference. |
| Theorem | syl3an2br 1137 | A syllogism inference. |
| Theorem | syl3an3br 1138 | A syllogism inference. |
| Theorem | syl3an 1139 | A triple syllogism inference. |
| Theorem | syl3anb 1140 | A triple syllogism inference. |
| Theorem | syl3anbr 1141 | A triple syllogism inference. |
| Theorem | syld3an3 1142 | A syllogism inference. |
| Theorem | syld3an1 1143 | A syllogism inference. |
| Theorem | syld3an2 1144 | A syllogism inference. |
| Theorem | syl3anl1 1145 | A syllogism inference. |
| Theorem | syl3anl2 1146 | A syllogism inference. |
| Theorem | syl3anl3 1147 | A syllogism inference. |
| Theorem | syl3anl 1148 | A triple syllogism inference. |
| Theorem | syl3anr1 1149 | A syllogism inference. |
| Theorem | syl3anr2 1150 | A syllogism inference. |
| Theorem | syl3anr3 1151 | A syllogism inference. |
| Theorem | 3impdi 1152 | Importation inference (undistribute conjunction). |
| Theorem | 3impdir 1153 | Importation inference (undistribute conjunction). |
| Theorem | 3anidm12 1154 | Inference from idempotent law for conjunction. |
| Theorem | 3anidm13 1155 | Inference from idempotent law for conjunction. |
| Theorem | 3anidm23 1156 | Inference from idempotent law for conjunction. |
| Theorem | 3ori 1157 | Infer implication from triple disjunction. |
| Theorem | 3jao 1158 | Disjunction of 3 antecedents. |
| Theorem | 3jaob 1159 | Disjunction of 3 antecedents. |
| Theorem | 3jaoi 1160 | Disjunction of 3 antecedents (inference). |
| Theorem | 3jaod 1161 | Disjunction of 3 antecedents (deduction). |
| Theorem | 3jaoian 1162 | Disjunction of 3 antecedents (inference). |
| Theorem | 3jaodan 1163 | Disjunction of 3 antecedents (deduction). |
| Theorem | 3jaao 1164 | Inference conjoining and disjoining the antecedents of three implications. (Contributed by Jeff Hankins, 15-Aug-2009.) (The proof was shortened by Andrew Salmon, 13-May-2011.) |
| Theorem | 3jaaoOLD 1165 | Inference conjoining and disjoining the antecedents of three implications. (Contributed by Jeff Hankins, 15-Aug-2009.) |
| Theorem | syl3an9b 1166 | Nested syllogism inference conjoining 3 dissimilar antecedents. |
| Theorem | 3orbi123d 1167 | Deduction joining 3 equivalences to form equivalence of disjunctions. |
| Theorem | 3anbi123d 1168 | Deduction joining 3 equivalences to form equivalence of conjunctions. |
| Theorem | 3anbi12d 1169 | Deduction conjoining and adding a conjunct to equivalences. |
| Theorem | 3anbi13d 1170 | Deduction conjoining and adding a conjunct to equivalences. |
| Theorem | 3anbi23d 1171 | Deduction conjoining and adding a conjunct to equivalences. |
| Theorem | 3anbi1d 1172 | Deduction adding conjuncts to an equivalence. |
| Theorem | 3anbi2d 1173 | Deduction adding conjuncts to an equivalence. |
| Theorem | 3anbi3d 1174 | Deduction adding conjuncts to an equivalence. |
| Theorem | 3anim123d 1175 | Deduction joining 3 implications to form implication of conjunctions. |
| Theorem | 3orim123d 1176 | Deduction joining 3 implications to form implication of disjunctions. |
| Theorem | an6 1177 | Rearrangement of 6 conjuncts. |
| Theorem | mp3an1 1178 | An inference based on modus ponens. |
| Theorem | mp3an2 1179 | An inference based on modus ponens. |
| Theorem | mp3an3 1180 | An inference based on modus ponens. |
| Theorem | mp3an12 1181 | An inference based on modus ponens. |
| Theorem | mp3an13 1182 | An inference based on modus ponens. |
| Theorem | mp3an23 1183 | An inference based on modus ponens. |
| Theorem | mp3an1i 1184 | An inference based on modus ponens. |
| Theorem | mp3anl1 1185 | An inference based on modus ponens. |
| Theorem | mp3anl2 1186 | An inference based on modus ponens. |
| Theorem | mp3anl3 1187 | An inference based on modus ponens. |
| Theorem | mp3anr1 1188 | An inference based on modus ponens. |
| Theorem | mp3anr2 1189 | An inference based on modus ponens. |
| Theorem | mp3anr3 1190 | An inference based on modus ponens. |
| Theorem | mp3an 1191 | An inference based on modus ponens. |
| Theorem | mpd3an3 1192 | An inference based on modus ponens. |
| Theorem | mpd3an23 1193 | An inference based on modus ponens. |
| Theorem | biimp3a 1194 | Infer implication from a logical equivalence. Similar to biimpa 460. |
| Theorem | biimp3ar 1195 | Infer implication from a logical equivalence. Similar to biimpar 461. |
| Theorem | 3anandis 1196 | Inference that undistributes a triple conjunction in the antecedent. |
| Theorem | 3anandirs 1197 | Inference that undistributes a triple conjunction in the antecedent. |
| Theorem | ecase23d 1198 | Deduction for elimination by cases. |
| Theorem | 3ecase 1199 | Inference for elimination by cases. |
| Other axiomatizations of classical propositional calculus | ||
| Derive the Lukasiewicz axioms from Meredith's sole axiom | ||
| Theorem | meredith 1200 |
Carew Meredith's sole axiom for propositional calculus. This amazing
formula is thought to be the shortest possible single axiom for
propositional calculus with inference rule ax-mp 7,
where negation and
implication are primitive. Here we prove Meredith's axiom from ax-1 4,
ax-2 5, and ax-3 6. Then from it we derive the Lukasiewicz
axioms
luk-1 1215, luk-2 1216, and luk-3 1217. Using these we finally re-derive our
axioms as ax1 1226, ax2 1227, and ax3 1228,
thus proving the equivalence of all
three systems. C. A. Meredith, "Single Axioms for the Systems (C,N),
(C,O) and (A,N) of the Two-Valued Propositional Calculus," The
Journal of
Computing Systems vol. 1 (1953), pp. 155-164. Meredith claimed to be
close to a proof that this axiom is the shortest possible, but the proof
was apparently never completed.
An obscure Irish lecturer, Meredith (1904-1976) became enamored with logic somewhat late in life after attending talks by Lukasiewicz and produced many remarkable results such as this axiom. From his obituary: "He did logic whenever time and opportunity presented themselves, and he did it on whatever materials came to hand: in a pub, his favored pint of porter within reach, he would use the inside of cigarette packs to write proofs for logical colleagues." (The proof was shortened by Andrew Salmon, 25-Jul-2011.) |
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