tom's blog

By tom, 6 years ago, In English

a 2-CNF formula is satisfiable if and only if there is no variable that belongs to the same strongly connected component as its negation..

Look at this example:







Any variable and its negation belong to the same strongly connected component, but it's not possible to satisfy these formulas.

What I'm doing wrong?

PS: With formula, I want to force x = 1

 
 
 
 
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6 years ago, # |
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If i remembered it correctly, for each a=>b you should also add -b=>-a edge

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    6 years ago, # ^ |
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    That was it. Thank you :)

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6 years ago, # |
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We can derive two implications from (avb): ¬a->b, ¬b->a.