Theorem List for Intuitionistic Logic Explorer - 701-800 *Has distinct variable
group(s)
| Type | Label | Description |
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| Theorem | pm4.15 701 |
Theorem *4.15 of [WhiteheadRussell] p.
117. (Contributed by NM,
3-Jan-2005.) (Proof shortened by Wolf Lammen, 18-Nov-2012.)
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| Theorem | pm5.21 702 |
Two propositions are equivalent if they are both false. Theorem *5.21 of
[WhiteheadRussell] p. 124.
(Contributed by NM, 21-May-1994.) (Revised by
Mario Carneiro, 31-Jan-2015.)
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| Theorem | pm5.21im 703 |
Two propositions are equivalent if they are both false. Closed form of
2false 708. Equivalent to a biimpr 130-like version of the xor-connective.
(Contributed by Wolf Lammen, 13-May-2013.) (Revised by Mario Carneiro,
31-Jan-2015.)
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| Theorem | nbn2 704 |
The negation of a wff is equivalent to the wff's equivalence to falsehood.
(Contributed by Juha Arpiainen, 19-Jan-2006.) (Revised by Mario Carneiro,
31-Jan-2015.)
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| Theorem | bibif 705 |
Transfer negation via an equivalence. (Contributed by NM, 3-Oct-2007.)
(Proof shortened by Wolf Lammen, 28-Jan-2013.)
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| Theorem | nbn 706 |
The negation of a wff is equivalent to the wff's equivalence to
falsehood. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Wolf
Lammen, 3-Oct-2013.)
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| Theorem | nbn3 707 |
Transfer falsehood via equivalence. (Contributed by NM,
11-Sep-2006.)
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| Theorem | 2false 708 |
Two falsehoods are equivalent. (Contributed by NM, 4-Apr-2005.)
(Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | 2falsed 709 |
Two falsehoods are equivalent (deduction form). (Contributed by NM,
11-Oct-2013.)
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| Theorem | pm5.21ni 710 |
Two propositions implying a false one are equivalent. (Contributed by
NM, 16-Feb-1996.) (Proof shortened by Wolf Lammen, 19-May-2013.)
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| Theorem | pm5.21nii 711 |
Eliminate an antecedent implied by each side of a biconditional.
(Contributed by NM, 21-May-1999.) (Revised by Mario Carneiro,
31-Jan-2015.)
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| Theorem | pm5.21ndd 712 |
Eliminate an antecedent implied by each side of a biconditional,
deduction version. (Contributed by Paul Chapman, 21-Nov-2012.)
(Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | pm5.19 713 |
Theorem *5.19 of [WhiteheadRussell] p.
124. (Contributed by NM,
3-Jan-2005.) (Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | pm4.8 714 |
Theorem *4.8 of [WhiteheadRussell] p.
122. This one holds for all
propositions, but compare with pm4.81dc 915 which requires a decidability
condition. (Contributed by NM, 3-Jan-2005.)
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| 1.2.6 Logical disjunction
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| Syntax | wo 715 |
Extend wff definition to include disjunction ('or').
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| Axiom | ax-io 716 |
Definition of 'or'. One of the axioms of propositional logic.
(Contributed by Mario Carneiro, 31-Jan-2015.) Use its alias jaob 717
instead. (New usage is discouraged.)
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| Theorem | jaob 717 |
Disjunction of antecedents. Compare Theorem *4.77 of [WhiteheadRussell]
p. 121. Alias of ax-io 716. (Contributed by NM, 30-May-1994.) (Revised
by Mario Carneiro, 31-Jan-2015.)
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| Theorem | olc 718 |
Introduction of a disjunct. Axiom *1.3 of [WhiteheadRussell] p. 96.
(Contributed by NM, 30-Aug-1993.) (Revised by NM, 31-Jan-2015.)
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| Theorem | orc 719 |
Introduction of a disjunct. Theorem *2.2 of [WhiteheadRussell] p. 104.
(Contributed by NM, 30-Aug-1993.) (Revised by NM, 31-Jan-2015.)
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| Theorem | pm2.67-2 720 |
Slight generalization of Theorem *2.67 of [WhiteheadRussell] p. 107.
(Contributed by NM, 3-Jan-2005.) (Revised by NM, 9-Dec-2012.)
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| Theorem | oibabs 721 |
Absorption of disjunction into equivalence. (Contributed by NM,
6-Aug-1995.) (Proof shortened by Wolf Lammen, 3-Nov-2013.)
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| Theorem | pm3.44 722 |
Theorem *3.44 of [WhiteheadRussell] p.
113. (Contributed by NM,
3-Jan-2005.) (Proof shortened by Wolf Lammen, 3-Oct-2013.)
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| Theorem | jaoi 723 |
Inference disjoining the antecedents of two implications. (Contributed
by NM, 5-Apr-1994.) (Revised by NM, 31-Jan-2015.)
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| Theorem | jaod 724 |
Deduction disjoining the antecedents of two implications. (Contributed
by NM, 18-Aug-1994.) (Revised by NM, 4-Apr-2013.)
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| Theorem | mpjaod 725 |
Eliminate a disjunction in a deduction. (Contributed by Mario Carneiro,
29-May-2016.)
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| Theorem | jaao 726 |
Inference conjoining and disjoining the antecedents of two implications.
(Contributed by NM, 30-Sep-1999.)
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| Theorem | jaoa 727 |
Inference disjoining and conjoining the antecedents of two implications.
(Contributed by Stefan Allan, 1-Nov-2008.)
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| Theorem | imorr 728 |
Implication in terms of disjunction. One direction of theorem *4.6 of
[WhiteheadRussell] p. 120. The
converse holds for decidable propositions,
as seen at imordc 904. (Contributed by Jim Kingdon, 21-Jul-2018.)
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| Theorem | pm2.53 729 |
Theorem *2.53 of [WhiteheadRussell] p.
107. This holds
intuitionistically, although its converse does not (see pm2.54dc 898).
(Contributed by NM, 3-Jan-2005.) (Revised by NM, 31-Jan-2015.)
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| Theorem | ori 730 |
Infer implication from disjunction. (Contributed by NM, 11-Jun-1994.)
(Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | ord 731 |
Deduce implication from disjunction. (Contributed by NM, 18-May-1994.)
(Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | orel1 732 |
Elimination of disjunction by denial of a disjunct. Theorem *2.55 of
[WhiteheadRussell] p. 107.
(Contributed by NM, 12-Aug-1994.) (Proof
shortened by Wolf Lammen, 21-Jul-2012.)
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| Theorem | orel2 733 |
Elimination of disjunction by denial of a disjunct. Theorem *2.56 of
[WhiteheadRussell] p. 107.
(Contributed by NM, 12-Aug-1994.) (Proof
shortened by Wolf Lammen, 5-Apr-2013.)
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| Theorem | pm1.4 734 |
Axiom *1.4 of [WhiteheadRussell] p.
96. (Contributed by NM, 3-Jan-2005.)
(Revised by NM, 15-Nov-2012.)
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| Theorem | orcom 735 |
Commutative law for disjunction. Theorem *4.31 of [WhiteheadRussell]
p. 118. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Wolf
Lammen, 15-Nov-2012.)
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| Theorem | orcomd 736 |
Commutation of disjuncts in consequent. (Contributed by NM,
2-Dec-2010.)
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| Theorem | orcoms 737 |
Commutation of disjuncts in antecedent. (Contributed by NM,
2-Dec-2012.)
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| Theorem | orci 738 |
Deduction introducing a disjunct. (Contributed by NM, 19-Jan-2008.)
(Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | olci 739 |
Deduction introducing a disjunct. (Contributed by NM, 19-Jan-2008.)
(Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | orcd 740 |
Deduction introducing a disjunct. (Contributed by NM, 20-Sep-2007.)
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| Theorem | olcd 741 |
Deduction introducing a disjunct. (Contributed by NM, 11-Apr-2008.)
(Proof shortened by Wolf Lammen, 3-Oct-2013.)
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| Theorem | orcs 742 |
Deduction eliminating disjunct. Notational convention: We sometimes
suffix with "s" the label of an inference that manipulates an
antecedent, leaving the consequent unchanged. The "s" means
that the
inference eliminates the need for a syllogism (syl 14)
-type inference
in a proof. (Contributed by NM, 21-Jun-1994.)
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| Theorem | olcs 743 |
Deduction eliminating disjunct. (Contributed by NM, 21-Jun-1994.)
(Proof shortened by Wolf Lammen, 3-Oct-2013.)
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| Theorem | pm2.07 744 |
Theorem *2.07 of [WhiteheadRussell] p.
101. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.45 745 |
Theorem *2.45 of [WhiteheadRussell] p.
106. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.46 746 |
Theorem *2.46 of [WhiteheadRussell] p.
106. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.47 747 |
Theorem *2.47 of [WhiteheadRussell] p.
107. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.48 748 |
Theorem *2.48 of [WhiteheadRussell] p.
107. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.49 749 |
Theorem *2.49 of [WhiteheadRussell] p.
107. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.67 750 |
Theorem *2.67 of [WhiteheadRussell] p.
107. (Contributed by NM,
3-Jan-2005.) (Revised by NM, 9-Dec-2012.)
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| Theorem | biorf 751 |
A wff is equivalent to its disjunction with falsehood. Theorem *4.74 of
[WhiteheadRussell] p. 121.
(Contributed by NM, 23-Mar-1995.) (Proof
shortened by Wolf Lammen, 18-Nov-2012.)
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| Theorem | biortn 752 |
A wff is equivalent to its negated disjunction with falsehood.
(Contributed by NM, 9-Jul-2012.)
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| Theorem | biorfi 753 |
A wff is equivalent to its disjunction with falsehood. (Contributed by
NM, 23-Mar-1995.)
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| Theorem | pm2.621 754 |
Theorem *2.621 of [WhiteheadRussell]
p. 107. (Contributed by NM,
3-Jan-2005.) (Revised by NM, 13-Dec-2013.)
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| Theorem | pm2.62 755 |
Theorem *2.62 of [WhiteheadRussell] p.
107. (Contributed by NM,
3-Jan-2005.) (Proof shortened by Wolf Lammen, 13-Dec-2013.)
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| Theorem | imorri 756 |
Infer implication from disjunction. (Contributed by Jonathan Ben-Naim,
3-Jun-2011.) (Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | pm4.52im 757 |
One direction of theorem *4.52 of [WhiteheadRussell] p. 120. The converse
also holds in classical logic. (Contributed by Jim Kingdon,
27-Jul-2018.)
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| Theorem | pm4.53r 758 |
One direction of theorem *4.53 of [WhiteheadRussell] p. 120. The converse
also holds in classical logic. (Contributed by Jim Kingdon,
27-Jul-2018.)
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| Theorem | ioran 759 |
Negated disjunction in terms of conjunction. This version of DeMorgan's
law is a biconditional for all propositions (not just decidable ones),
unlike oranim 788, anordc 964, or ianordc 906. Compare Theorem *4.56 of
[WhiteheadRussell] p. 120.
(Contributed by NM, 5-Aug-1993.) (Revised by
Mario Carneiro, 31-Jan-2015.)
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| Theorem | pm3.14 760 |
Theorem *3.14 of [WhiteheadRussell] p.
111. One direction of De Morgan's
law). The biconditional holds for decidable propositions as seen at
ianordc 906. The converse holds for decidable
propositions, as seen at
pm3.13dc 967. (Contributed by NM, 3-Jan-2005.) (Revised
by Mario
Carneiro, 31-Jan-2015.)
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| Theorem | pm3.1 761 |
Theorem *3.1 of [WhiteheadRussell] p.
111. The converse holds for
decidable propositions, as seen at anordc 964. (Contributed by NM,
3-Jan-2005.) (Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | jao 762 |
Disjunction of antecedents. Compare Theorem *3.44 of [WhiteheadRussell]
p. 113. (Contributed by NM, 5-Apr-1994.) (Proof shortened by Wolf
Lammen, 4-Apr-2013.)
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| Theorem | pm1.2 763 |
Axiom *1.2 (Taut) of [WhiteheadRussell] p. 96. (Contributed by
NM,
3-Jan-2005.) (Revised by NM, 10-Mar-2013.)
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| Theorem | oridm 764 |
Idempotent law for disjunction. Theorem *4.25 of [WhiteheadRussell]
p. 117. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Andrew
Salmon, 16-Apr-2011.) (Proof shortened by Wolf Lammen, 10-Mar-2013.)
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| Theorem | pm4.25 765 |
Theorem *4.25 of [WhiteheadRussell] p.
117. (Contributed by NM,
3-Jan-2005.)
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| Theorem | orim12i 766 |
Disjoin antecedents and consequents of two premises. (Contributed by
NM, 6-Jun-1994.) (Proof shortened by Wolf Lammen, 25-Jul-2012.)
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| Theorem | orim1i 767 |
Introduce disjunct to both sides of an implication. (Contributed by NM,
6-Jun-1994.)
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| Theorem | orim2i 768 |
Introduce disjunct to both sides of an implication. (Contributed by NM,
6-Jun-1994.)
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| Theorem | orbi2i 769 |
Inference adding a left disjunct to both sides of a logical equivalence.
(Contributed by NM, 5-Aug-1993.) (Proof shortened by Wolf Lammen,
12-Dec-2012.)
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| Theorem | orbi1i 770 |
Inference adding a right disjunct to both sides of a logical
equivalence. (Contributed by NM, 5-Aug-1993.)
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| Theorem | orbi12i 771 |
Infer the disjunction of two equivalences. (Contributed by NM,
5-Aug-1993.)
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| Theorem | pm1.5 772 |
Axiom *1.5 (Assoc) of [WhiteheadRussell] p. 96. (Contributed by
NM,
3-Jan-2005.)
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| Theorem | or12 773 |
Swap two disjuncts. (Contributed by NM, 5-Aug-1993.) (Proof shortened by
Wolf Lammen, 14-Nov-2012.)
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| Theorem | orass 774 |
Associative law for disjunction. Theorem *4.33 of [WhiteheadRussell]
p. 118. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Andrew
Salmon, 26-Jun-2011.)
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| Theorem | pm2.31 775 |
Theorem *2.31 of [WhiteheadRussell] p.
104. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.32 776 |
Theorem *2.32 of [WhiteheadRussell] p.
105. (Contributed by NM,
3-Jan-2005.)
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| Theorem | or32 777 |
A rearrangement of disjuncts. (Contributed by NM, 18-Oct-1995.) (Proof
shortened by Andrew Salmon, 26-Jun-2011.)
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| Theorem | or4 778 |
Rearrangement of 4 disjuncts. (Contributed by NM, 12-Aug-1994.)
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| Theorem | or42 779 |
Rearrangement of 4 disjuncts. (Contributed by NM, 10-Jan-2005.)
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| Theorem | orordi 780 |
Distribution of disjunction over disjunction. (Contributed by NM,
25-Feb-1995.)
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| Theorem | orordir 781 |
Distribution of disjunction over disjunction. (Contributed by NM,
25-Feb-1995.)
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| Theorem | pm2.3 782 |
Theorem *2.3 of [WhiteheadRussell] p.
104. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.41 783 |
Theorem *2.41 of [WhiteheadRussell] p.
106. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.42 784 |
Theorem *2.42 of [WhiteheadRussell] p.
106. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm2.4 785 |
Theorem *2.4 of [WhiteheadRussell] p.
106. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm4.44 786 |
Theorem *4.44 of [WhiteheadRussell] p.
119. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm4.56 787 |
Theorem *4.56 of [WhiteheadRussell] p.
120. (Contributed by NM,
3-Jan-2005.)
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| Theorem | oranim 788 |
Disjunction in terms of conjunction (DeMorgan's law). One direction of
Theorem *4.57 of [WhiteheadRussell] p. 120. The converse
does not hold
intuitionistically but does hold in classical logic. (Contributed by Jim
Kingdon, 25-Jul-2018.)
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| Theorem | pm4.78i 789 |
Implication distributes over disjunction. One direction of Theorem *4.78
of [WhiteheadRussell] p. 121.
The converse holds in classical logic.
(Contributed by Jim Kingdon, 15-Jan-2018.)
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| Theorem | mtord 790 |
A modus tollens deduction involving disjunction. (Contributed by Jeff
Hankins, 15-Jul-2009.) (Revised by Mario Carneiro, 31-Jan-2015.)
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| Theorem | pm4.45 791 |
Theorem *4.45 of [WhiteheadRussell] p.
119. (Contributed by NM,
3-Jan-2005.)
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| Theorem | pm3.48 792 |
Theorem *3.48 of [WhiteheadRussell] p.
114. (Contributed by NM,
28-Jan-1997.) (Revised by NM, 1-Dec-2012.)
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| Theorem | orim12d 793 |
Disjoin antecedents and consequents in a deduction. (Contributed by NM,
10-May-1994.)
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| Theorem | orim1d 794 |
Disjoin antecedents and consequents in a deduction. (Contributed by NM,
23-Apr-1995.)
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| Theorem | orim2d 795 |
Disjoin antecedents and consequents in a deduction. (Contributed by NM,
23-Apr-1995.)
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| Theorem | orim2 796 |
Axiom *1.6 (Sum) of [WhiteheadRussell]
p. 97. (Contributed by NM,
3-Jan-2005.)
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| Theorem | orbi2d 797 |
Deduction adding a left disjunct to both sides of a logical equivalence.
(Contributed by NM, 5-Aug-1993.) (Revised by Mario Carneiro,
31-Jan-2015.)
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| Theorem | orbi1d 798 |
Deduction adding a right disjunct to both sides of a logical
equivalence. (Contributed by NM, 5-Aug-1993.)
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| Theorem | orbi1 799 |
Theorem *4.37 of [WhiteheadRussell] p.
118. (Contributed by NM,
3-Jan-2005.)
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| Theorem | orbi12d 800 |
Deduction joining two equivalences to form equivalence of disjunctions.
(Contributed by NM, 5-Aug-1993.)
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