Metamath Proof Explorer


Theorem subid1d

Description: Identity law for subtraction. (Contributed by Mario Carneiro, 27-May-2016)

Ref Expression
Hypothesis negidd.1 φ A
Assertion subid1d φ A 0 = A

Proof

Step Hyp Ref Expression
1 negidd.1 φ A
2 subid1 A A 0 = A
3 1 2 syl φ A 0 = A