theorem Th29: :: EQREL_1:29

for X being set
for EqR1, EqR2, E being Equivalence_Relation of X st E = EqR1 \/ EqR2 holds
for x being object holds
( not x in X or Class (E,x) = Class (EqR1,x) or Class (E,x) = Class (EqR2,x) )