Here you can ask questions and find or give answers to organizational, academic and other questions about studying computer science.

1.1k questions

1.2k answers


538 users

0 votes


I have doubt regarding sequent calculus. How can i find the counter example?  I have written down the solution with counter examples, could you please help to solve this problem?

check the validity of !!((c->a)->b)


in # Study-Organisation (Master) by (2.7k points)

1 Answer

+1 vote
Best answer
You have replaced (c->a)->b by !(!c&a)&a, but it should be rather !(!c|a)|a since an implication phi->psi can be defined as !phi | psi.
by (166k points)
selected by
got it..after that how i can find the counterexample?
Well, have a look at the slides. Every leaf node where the two sets of formulas are disjoint gives you an assignment of the variables.
Imprint | Privacy Policy