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Statement List for Metamath Proof Explorer - 601-700 - Page 7 of 58
TypeLabelDescription
Statement
 
Theorem3mix2 601 Introduction in triple disjunction.
|- (ph -> (ps \/ ph \/ ch))
 
Theorem3mix3 602 Introduction in triple disjunction.
|- (ph -> (ps \/ ch \/ ph))
 
Theorem3pm3.2i 603 Infer conjunction of premises.
|- ph   &   |- ps   &   |- ch   =>   |- (ph /\ ps /\ ch)
 
Theorem3jca 604 Join consequents with conjunction.
|- (ph -> ps)   &   |- (ph -> ch)   &   |- (ph -> th)   =>   |- (ph -> (ps /\ ch /\ th))
 
Theoremim3an 605 Join antecedents and consequents with conjunction.
|- (ph -> ps)   &   |- (ch -> th)   &   |- (ta -> et)   =>   |- ((ph /\ ch /\ ta ) -> (ps /\ th /\ et))
 
Theorembi3an 606 Join 3 biconditionals with conjunction.
|- (ph <-> ps)   &   |- (ch <-> th)   &   |- (ta <-> et)   =>   |- ((ph /\ ch /\ ta ) <-> (ps /\ th /\ et))
 
Theorembi3or 607 Join antecedents and consequents with disjunction.
|- (ph <-> ps)   &   |- (ch <-> th)   &   |- (ta <-> et)   =>   |- ((ph \/ ch \/ ta ) <-> (ps \/ th \/ et))
 
Theorem3imp 608 Importation inference.
|- (ph -> (ps -> (ch -> th)))   =>   |- ((ph /\ ps /\ ch) -> th)
 
Theorem3impa 609 Importation from double to triple conjunction.
|- (((ph /\ ps) /\ ch) -> th)   =>   |- ((ph /\ ps /\ ch) -> th)
 
Theorem3impb 610 Importation from double to triple conjunction.
|- ((ph /\ (ps /\ ch)) -> th)   =>   |- ((ph /\ ps /\ ch) -> th)
 
Theorem3exp 611 Exportation inference.
|- ((ph /\ ps /\ ch) -> th)   =>   |- (ph -> (ps -> (ch -> th)))
 
Theorem3expa 612 Exportation from triple to double conjunction.
|- ((ph /\ ps /\ ch) -> th)   =>   |- (((ph /\ ps) /\ ch) -> th)
 
Theorem3expb 613 Exportation from triple to double conjunction.
|- ((ph /\ ps /\ ch) -> th)   =>   |- ((ph /\ (ps /\ ch)) -> th)
 
Theorem3com12 614 Commutation in antecedent. Swap 1st and 3rd.
|- ((ph /\ ps /\ ch) -> th)   =>   |- ((ps /\ ph /\ ch) -> th)
 
Theorem3com13 615 Commutation in antecedent. Swap 1st and 3rd.
|- ((ph /\ ps /\ ch) -> th)   =>   |- ((ch /\ ps /\ ph) -> th)
 
Theorem3com23 616 Commutation in antecedent. Swap 2nd and 3rd.
|- ((ph /\ ps /\ ch) -> th)   =>   |- ((ph /\ ch /\ ps) -> th)
 
Theorem3coml 617 Commutation in antecedent. Rotate left.
|- ((ph /\ ps /\ ch) -> th)   =>   |- ((ps /\ ch /\ ph) -> th)
 
Theorem3comr 618 Commutation in antecedent. Rotate right.
|- ((ph /\ ps /\ ch) -> th)   =>   |- ((ch /\ ph /\ ps) -> th)
 
Theoremsyl3an1 619 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta -> ph)   =>   |- ((ta /\ ps /\ ch) -> th)
 
Theoremsyl3an2 620 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta -> ps)   =>   |- ((ph /\ ta /\ ch) -> th)
 
Theoremsyl3an3 621 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta -> ch)   =>   |- ((ph /\ ps /\ ta ) -> th)
 
Theoremsyl3an1b 622 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta <-> ph)   =>   |- ((ta /\ ps /\ ch) -> th)
 
Theoremsyl3an2b 623 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta <-> ps)   =>   |- ((ph /\ ta /\ ch) -> th)
 
Theoremsyl3an3b 624 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta <-> ch)   =>   |- ((ph /\ ps /\ ta ) -> th)
 
Theoremsyl3an1br 625 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ph <-> ta )   =>   |- ((ta /\ ps /\ ch) -> th)
 
Theoremsyl3an2br 626 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ps <-> ta )   =>   |- ((ph /\ ta /\ ch) -> th)
 
Theoremsyl3an3br 627 A syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ch <-> ta )   =>   |- ((ph /\ ps /\ ta ) -> th)
 
Theoremsyl3an 628 A triple syllogism inference.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta -> ph)   &   |- (et -> ps)   &   |- (ze -> ch)   =>   |- ((ta /\ et /\ ze) -> th)
 
Theoremsyl3anc 629 A syllogism inference combined with contraction.
|- ((ph /\ ps /\ ch) -> th)   &   |- (ta -> ph)   &   |- (ta -> ps)   &   |- (ta -> ch)   =>   |- (ta -> th)
 
Theorem3impdi 630 Importation inference (undistribute conjunction).
|- (((ph /\ ps) /\ (ph /\ ch)) -> th)   =>   |- ((ph /\ ps /\ ch) -> th)
 
Theorem3impdir 631 Importation inference (undistribute conjunction).
|- (((ph /\ ps) /\ (ch /\ ps)) -> th)   =>   |- ((ph /\ ch /\ ps) -> th)
 
Theorem3jao 632 Disjunction of 3 antecedents.
|- (((ph -> ps) /\ (ch -> ps) /\ (th -> ps)) -> ((ph \/ ch \/ th) -> ps))
 
Theorem3jaoi 633 Disjunction of 3 antecedents (inference).
|- (ph -> ps)   &   |- (ch -> ps)   &   |- (th -> ps)   =>   |- ((ph \/ ch \/ th) -> ps)
 
Theoremsyl3an9b 634 Nested syllogism inference conjoining 3 dissimilar antecedents.
|- (ph -> (ps <-> ch))   &   |- (th -> (ch <-> ta ))   &   |- (et -> (ta <-> ze))   =>   |- ((ph /\ th /\ et) -> (ps <-> ze))
 
Theorembi3ord 635 Deduction joining 3 equivalences to form equivalence of disjunctions.
|- (ph -> (ps <-> ch))   &   |- (ph -> (th <-> ta ))   &   |- (ph -> (et <-> ze))   =>   |- (ph -> ((ps \/ th \/ et) <-> (ch \/ ta \/ ze)))
 
Theorembi3and 636 Deduction joining 3 equivalences to form equivalence of conjunctions.
|- (ph -> (ps <-> ch))   &   |- (ph -> (th <-> ta ))   &   |- (ph -> (et <-> ze))   =>   |- (ph -> ((ps /\ th /\ et) <-> (ch /\ ta /\ ze)))
 
Theoremim3ord 637 Deduction joining 3 implications to form implication of disjunctions.
|- (ph -> (ps -> ch))   &   |- (ph -> (th -> ta ))   &   |- (ph -> (et -> ze))   =>   |- (ph -> ((ps \/ th \/ et) -> (ch \/ ta \/ ze)))
 
Theoreman6 638 Rearrangement of 6 conjuncts.
|- (((ph /\ ps /\ ch) /\ (th /\ ta /\ et)) <-> ((ph /\ th) /\ (ps /\ ta ) /\ (ch /\ et)))
 
Theoremmp3an1 639 An inference based on modus ponens.
|- ph   &   |- ((ph /\ ps /\ ch) -> th)   =>   |- ((ps /\ ch) -> th)
 
Theoremmp3an2 640 An inference based on modus ponens.
|- ps   &   |- ((ph /\ ps /\ ch) -> th)   =>   |- ((ph /\ ch) -> th)
 
Theoremmp3an3 641 An inference based on modus ponens.
|- ch   &   |- ((ph /\ ps /\ ch) -> th)   =>   |- ((ph /\ ps) -> th)
 
Theoremmp3an 642 An inference based on modus ponens.
|- ph   &   |- ps   &   |- ch   &   |- ((ph /\ ps /\ ch) -> th)   =>   |- th
 
Theoremecased 643 Deduction for elimination by cases.
|- (ph -> (ps \/ ch \/ th))   &   |- (ph -> -. ch)   &   |- (ph -> -. th)   =>   |- (ph -> ps)
 
Theoremmeredith 644 Carew Meredith's sole axiom for propositional calculus. This amazing formula is thought to be the shortest possible single axiom for propositional calculus using negation, implication, and inference rule ax-mp 6. Here we prove Meredith's axiom from ax-1 3, ax-2 4, and ax-3 5. Then from it we derive the Lukasiewicz axioms luk-1 658, luk-2 659, and luk-3 660. Using these we finally re-derive our axioms as ax1 669, ax2 670, and ax3 671, 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. 3 (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."

|- (((((ph -> ps) -> (-. ch -> -. th)) -> ch) -> ta ) -> ((ta -> ph) -> (th -> ph)))
 
Theoremmerlem1 645 Step 3 of Meredith's proof of Lukasiewicz axioms from his sole axiom. (The step numbers refer to Meredith's original paper.)
|- (((ch -> (-. ph -> ps)) -> ta ) -> (ph -> ta ))
 
Theoremmerlem2 646 Step 4 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (((ph -> ph) -> ch) -> (th -> ch))
 
Theoremmerlem3 647 Step 7 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (((ps -> ch) -> ph) -> (ch -> ph))
 
Theoremmerlem4 648 Step 8 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (ta -> ((ta -> ph) -> (th -> ph)))
 
Theoremmerlem5 649 Step 11 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- ((ph -> ps) -> (-. -. ph -> ps))
 
Theoremmerlem6 650 Step 12 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (ch -> (((ps -> ch) -> ph) -> (th -> ph)))
 
Theoremmerlem7 651 Between steps 14 and 15 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (ph -> (((ps -> ch) -> th) -> (((ch -> ta ) -> (-. th -> -. ps)) -> th)))
 
Theoremmerlem8 652 Step 15 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (((ps -> ch) -> th) -> (((ch -> ta ) -> (-. th -> -. ps)) -> th))
 
Theoremmerlem9 653 Step 18 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- (((ph -> ps) -> (ch -> (th -> (ps -> ta )))) -> (et -> (ch -> (th -> (ps -> ta )))))
 
Theoremmerlem10 654 Step 19 of Meredith's proof of Lukasiewicz axioms from his sole axiom.
|- ((ph -> (ph ->