What is the difference between a "proof by contradiction" and "proving the contrapositive"? Intuitive, it feels like doing the exact same thing. And when I compare an exercise, one person …

My question tries to address the intuition or situations when using the contrapositive to prove a mathematical statement is an adequate attempt. Whenever we have a mathematical …

Feb 7, 2017 · I'm understanding the basic idea of contraposition, when it comes to propositional logic and writing proofs, but I'm having trouble figuring out what the contraposition of "P if and …

Jul 30, 2020 · Contraposition on the implication inside the statement is a special case of proof by contradiction where one assumes ¬Q ¬ Q and P P, derives a contradiction (not necessarily to …

Aug 31, 2019 · You can use a proof by contraposition whenever you have an implication to prove. A good guideline for when you maybe should use a proof by contraposition is when the …

Jul 13, 2015 · I wanted to ask (as the title suggests) why the law of contraposition is a tautology. My book states that a tautology is a statement which is true for the all the values of the …

Aug 6, 2018 · Remark. Both proofs by contraposition and proofs by contradiction are valid in classical logic, but in general they are not valid in intuitionistic logic (roughly speaking, a …

Jan 15, 2015 · I know that $2\left (2k + 2\right) + 1$ means that the number is odd and the contraposition has now be proofed. And I understand that we got to $2\left (3k+2\right)+1$, …

Prove directly, by contradiction, or contraposition? If the product of two integers is even, at least one of them must be even.

Direct proof of a contraposition Ask Question Asked 12 years ago Modified 12 years ago