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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | 3mix2 601 | Introduction in triple disjunction. |
| Theorem | 3mix3 602 | Introduction in triple disjunction. |
| Theorem | 3pm3.2i 603 | Infer conjunction of premises. |
| Theorem | 3jca 604 | Join consequents with conjunction. |
| Theorem | im3an 605 | Join antecedents and consequents with conjunction. |
| Theorem | bi3an 606 | Join 3 biconditionals with conjunction. |
| Theorem | bi3or 607 | Join antecedents and consequents with disjunction. |
| Theorem | 3imp 608 | Importation inference. |
| Theorem | 3impa 609 | Importation from double to triple conjunction. |
| Theorem | 3impb 610 | Importation from double to triple conjunction. |
| Theorem | 3exp 611 | Exportation inference. |
| Theorem | 3expa 612 | Exportation from triple to double conjunction. |
| Theorem | 3expb 613 | Exportation from triple to double conjunction. |
| Theorem | 3com12 614 | Commutation in antecedent. Swap 1st and 3rd. |
| Theorem | 3com13 615 | Commutation in antecedent. Swap 1st and 3rd. |
| Theorem | 3com23 616 | Commutation in antecedent. Swap 2nd and 3rd. |
| Theorem | 3coml 617 | Commutation in antecedent. Rotate left. |
| Theorem | 3comr 618 | Commutation in antecedent. Rotate right. |
| Theorem | syl3an1 619 | A syllogism inference. |
| Theorem | syl3an2 620 | A syllogism inference. |
| Theorem | syl3an3 621 | A syllogism inference. |
| Theorem | syl3an1b 622 | A syllogism inference. |
| Theorem | syl3an2b 623 | A syllogism inference. |
| Theorem | syl3an3b 624 | A syllogism inference. |
| Theorem | syl3an1br 625 | A syllogism inference. |
| Theorem | syl3an2br 626 | A syllogism inference. |
| Theorem | syl3an3br 627 | A syllogism inference. |
| Theorem | syl3an 628 | A triple syllogism inference. |
| Theorem | syl3anc 629 | A syllogism inference combined with contraction. |
| Theorem | 3impdi 630 | Importation inference (undistribute conjunction). |
| Theorem | 3impdir 631 | Importation inference (undistribute conjunction). |
| Theorem | 3jao 632 | Disjunction of 3 antecedents. |
| Theorem | 3jaoi 633 | Disjunction of 3 antecedents (inference). |
| Theorem | syl3an9b 634 | Nested syllogism inference conjoining 3 dissimilar antecedents. |
| Theorem | bi3ord 635 | Deduction joining 3 equivalences to form equivalence of disjunctions. |
| Theorem | bi3and 636 | Deduction joining 3 equivalences to form equivalence of conjunctions. |
| Theorem | im3ord 637 | Deduction joining 3 implications to form implication of disjunctions. |
| Theorem | an6 638 | Rearrangement of 6 conjuncts. |
| Theorem | mp3an1 639 | An inference based on modus ponens. |
| Theorem | mp3an2 640 | An inference based on modus ponens. |
| Theorem | mp3an3 641 | An inference based on modus ponens. |
| Theorem | mp3an 642 | An inference based on modus ponens. |
| Theorem | ecased 643 | Deduction for elimination by cases. |
| Theorem | meredith 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." |
| Theorem | merlem1 645 | Step 3 of Meredith's proof of Lukasiewicz axioms from his sole axiom. (The step numbers refer to Meredith's original paper.) |
| Theorem | merlem2 646 | Step 4 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem3 647 | Step 7 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem4 648 | Step 8 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem5 649 | Step 11 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem6 650 | Step 12 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem7 651 | Between steps 14 and 15 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem8 652 | Step 15 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem9 653 | Step 18 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |
| Theorem | merlem10 654 | Step 19 of Meredith's proof of Lukasiewicz axioms from his sole axiom. |