Need Urgent help in mathematical logic problem

Zoro November 24, 2018 at 18:38 1275 views 1 comments Logic & Philosophy of Mathematics
Hi, I need Urgent help in mathematical logic problem..
Prove: Given a wff A and v, v’ some valuations, if for each p ? At(A)
v(p) = v’(p) then v(A) = v’(A)

Comments (1)

Mentalusion November 26, 2018 at 16:29 ¶ #231384
It looks like you're trying to prove a substitution lemma, or something involving the substitution lemma (I'm assuming I understand the notation you're using). If I recall correctly, the proof proceeds by induction on the structure of the WFF. So, you will assume the truth of the antecedent, i.e. that for each p ? At(A), that v(p) = v'(p), then show the truth for each case of the WFF given the assumed truth of the antecedent and the rules for substitution....I think. Happy to be corrected if wrong.
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