# Thread: Natural Deduction in propositional logic

1. ## Natural Deduction in propositional logic

I am trying to solve this but I am not too sure whether I am doing this right

p V ( q ʌ r)
----------
p V q

and I know this can be proved using V-E rule.

But I just don't know the step maybe because i am new to this thing. Please help me..

2. ## Re: Natural Deduction in propositional logic

There are several flavors of natural deduction: Fitch style, tree style with formulas as nodes and tree style with sequents as nodes. The following is a derivation in tree style with formulas (the picture is clickable).

Fee free to ask further questions if this format is not clear.

3. ## Re: Natural Deduction in propositional logic

if you don't mind could you please represent this in Fitch style so that I can check whether I 've got this right? thank you very much Mr. emakarov!

4. ## Re: Natural Deduction in propositional logic

Fitch style is something like this.

Code:
1. p \/ (q /\ r)	Assumption
2.   p			Assumption
3.   p \/ q		2, \/I
4.   q /\ r		Assumption
5.   q			4, /\E
6.   p \/ q		5, \/I
7. p \/ q		1,2-3,4-6, \/E