Theorem entr4i

Description: A chained equinumerosity inference. (Contributed by NM, 25-Sep-2004)

	Ref	Expression
Hypotheses	entr4i.1	$$⊢A\approx B$$
	entr4i.2	$$⊢C\approx B$$
Assertion	entr4i	$$⊢A\approx C$$

Proof

Step	Hyp	Ref	Expression
1		entr4i.1	$$⊢A\approx B$$
2		entr4i.2	$$⊢C\approx B$$
3	2	ensymi	$$⊢B\approx C$$
4	1 3	entri	$$⊢A\approx C$$