Theorem subidi

Description: Subtraction of a number from itself. (Contributed by NM, 26-Nov-1994)

	Ref	Expression
Hypothesis	negidi.1	|- A e. CC
Assertion	subidi	|- ( A - A ) = 0

Proof

Step	Hyp	Ref	Expression
1		negidi.1	|- A e. CC
2		subid	|- ( A e. CC -> ( A - A ) = 0 )
3	1 2	ax-mp	|- ( A - A ) = 0