Homework 5

Due Thursday, March 9 at the start of class.

Prove the following sequents in the Logic of Elementary Arithmetic:

1. (y=0) & (y=x) |- 0=x
2. (x=0) v ((x+x)>0) |- (y=(x+x)) -> ((y>0) v (y=(0+x)))
3. |- (2+1)=(1+2)
4. (x+1)=y |- (x+2)=((y+0)+1)
5. |- (a+0)=(0+a)