Theorem mnfnepnf

Description: Minus and plus infinity are different. (Contributed by David A. Wheeler, 8-Dec-2018)

	Ref	Expression
Assertion	mnfnepnf	⊢ -∞ ≠ +∞

Proof

Step	Hyp	Ref	Expression
1		pnfnemnf	⊢ +∞ ≠ -∞
2	1	necomi	⊢ -∞ ≠ +∞