Metamath Proof Explorer

Theorem tpidm13

Description: Unordered triple { A , B , A } is just an overlong way to write { A , B } . (Contributed by David A. Wheeler, 10-May-2015)

Ref Expression
Assertion tpidm13 
|- { A , B , A } = { A , B }

Proof

Step Hyp Ref Expression
1 tprot 
 |-  { A , A , B } = { A , B , A }
2 tpidm12 
 |-  { A , A , B } = { A , B }
3 1 2 eqtr3i 
 |-  { A , B , A } = { A , B }