Metamath Proof Explorer


Theorem dmcoss2

Description: The domain of cosets is the range. (Contributed by Peter Mazsa, 27-Dec-2018)

Ref Expression
Assertion dmcoss2 dom R = ran R

Proof

Step Hyp Ref Expression
1 dmcoss3 dom R = dom R -1
2 df-rn ran R = dom R -1
3 1 2 eqtr4i dom R = ran R