1.

A branch of a tableau contains $x[Fax®"y[GbyÙ¬b=a]] and a=b.

List all the formulae which could be added by using the left hand identity rule.

List all the formulae which could be added by using the right hand identity rule.

2.

Consider the following tableau:

1          ¬a=c
2          a=b
3          c=a

There are many ways of adding a fourth line. List them all, closing the tableau where appropriate.