Metamath Proof Explorer


Theorem subsvald

Description: The value of surreal subtraction. (Contributed by Scott Fenton, 5-Feb-2025)

Ref Expression
Hypotheses subsvald.1 φ A No
subsvald.2 φ B No
Assertion subsvald φ A - s B = A + s + s B

Proof

Step Hyp Ref Expression
1 subsvald.1 φ A No
2 subsvald.2 φ B No
3 subsval A No B No A - s B = A + s + s B
4 1 2 3 syl2anc φ A - s B = A + s + s B