Theorem negsval2d

Description: Surreal negation in terms of subtraction. (Contributed by Scott Fenton, 15-Apr-2025)

	Ref	Expression
Hypothesis	negsval2d.1	|- ( ph -> A e. No )
Assertion	negsval2d	|- ( ph -> ( -us ` A ) = ( 0s -s A ) )

Proof

Step	Hyp	Ref	Expression
1		negsval2d.1	|- ( ph -> A e. No )
2		negsval2	|- ( A e. No -> ( -us ` A ) = ( 0s -s A ) )
3	1 2	syl	|- ( ph -> ( -us ` A ) = ( 0s -s A ) )