I could easily prove   $\neg P \lor Q$ entails $P \rightarrow Q$.  It is well known that   $P \rightarrow Q$ entails $\neg P \lor Q$  but I couldn't find a way to prove it.   Although there is the same question;  ; it's a little bit confusing and I need to see step by step solution.  Could you show me the way by using Natural Deduction?
In my book about Logic, which is called 'Language, Proof and Logic', by the way, there is explained that the conditional $ P \rightarrow Q $ is equivalent with $\neg P \lor Q$.   that gives as answer: 'just compare the truth tables and you can see that they are equivalent'. However, I would like to know how to prove this using formal propositional logic. This should be possible, right?
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