let D be non empty set ; for RD being Equivalence_Relation of D
for d being Element of D
for F being BinOp of D,RD st d is_a_unity_wrt F holds
EqClass (RD,d) is_a_unity_wrt F /\/ RD
let RD be Equivalence_Relation of D; for d being Element of D
for F being BinOp of D,RD st d is_a_unity_wrt F holds
EqClass (RD,d) is_a_unity_wrt F /\/ RD
let d be Element of D; for F being BinOp of D,RD st d is_a_unity_wrt F holds
EqClass (RD,d) is_a_unity_wrt F /\/ RD
let F be BinOp of D,RD; ( d is_a_unity_wrt F implies EqClass (RD,d) is_a_unity_wrt F /\/ RD )
assume that
A1:
d is_a_left_unity_wrt F
and
A2:
d is_a_right_unity_wrt F
; BINOP_1:def 7 EqClass (RD,d) is_a_unity_wrt F /\/ RD
thus
( EqClass (RD,d) is_a_left_unity_wrt F /\/ RD & EqClass (RD,d) is_a_right_unity_wrt F /\/ RD )
by A1, A2, Th6, Th7; BINOP_1:def 7 verum