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So i've been stuck on this problem for about an hour. I can't figure out how to do it, and help would be absolutely amazing. This is what's given:

$0 + 1 = 1$

$\forall x (x + 0 = x)$

$\forall x \forall y [x + (y+1)= (x+y)+1]$

$[0 + 1 = 1 + 0 \wedge \forall x(x + 1 = 1 + x \rightarrow (x+1)+1 = 1+(x+1)))] \rightarrow \forall x (x+1=1+x)$

And with these premises, I need to get $\forall x (x+1=1+x)$.

Help would be great. I keep getting closeish, only to find I'm actually doing it totally wrong.

  • 9
    Sometimes it's good to give yourself more than an hour!2010-12-02

3 Answers 3