Metamath Proof Explorer


Theorem ttcpwss

Description: The transitive closure of a power class is contained in the power class of the transitive closure. (Contributed by Matthew House, 6-Apr-2026)

Ref Expression
Assertion ttcpwss
|- TC+ ~P A C_ ~P TC+ A

Proof

Step Hyp Ref Expression
1 ttcid
 |-  A C_ TC+ A
2 1 sspwi
 |-  ~P A C_ ~P TC+ A
3 ttctr
 |-  Tr TC+ A
4 pwtr
 |-  ( Tr TC+ A <-> Tr ~P TC+ A )
5 3 4 mpbi
 |-  Tr ~P TC+ A
6 ttcmin
 |-  ( ( ~P A C_ ~P TC+ A /\ Tr ~P TC+ A ) -> TC+ ~P A C_ ~P TC+ A )
7 2 5 6 mp2an
 |-  TC+ ~P A C_ ~P TC+ A