Theorem negscld

Description: The surreals are closed under negation. Theorem 6(ii) of Conway p. 18. (Contributed by Scott Fenton, 3-Feb-2025)

	Ref	Expression
Hypothesis	negscld.1	$$⊢\phi \to A\in \mathrm{No}$$
Assertion	negscld	Could not format assertion : No typesetting found for |- ( ph -> ( -us ` A ) e. No ) with typecode |-

Proof

Step	Hyp	Ref	Expression
1		negscld.1	$$⊢\phi \to A\in \mathrm{No}$$
2		negscl	Could not format ( A e. No -> ( -us ` A ) e. No ) : No typesetting found for |- ( A e. No -> ( -us ` A ) e. No ) with typecode |-
3	1 2	syl	Could not format ( ph -> ( -us ` A ) e. No ) : No typesetting found for |- ( ph -> ( -us ` A ) e. No ) with typecode |-