Theorem tr0

Description: The empty set is transitive. (Contributed by NM, 16-Sep-1993)

	Ref	Expression
Assertion	tr0	|- Tr (/)

Proof

Step	Hyp	Ref	Expression
1		0ss	|- (/) C_ ~P (/)
2		dftr4	|- ( Tr (/) <-> (/) C_ ~P (/) )
3	1 2	mpbir	|- Tr (/)