let U1, U2 be Universal_Algebra; ( U1,U2 are_similar implies for o being OperSymbol of (MSSign U1) holds Den o,((MSAlg U2) Over (MSSign U1)) is operation of U2 )
set A = (MSAlg U2) Over (MSSign U1);
A1:
MSAlg U2 = MSAlgebra(# (MSSorts U2),(MSCharact U2) #)
by MSUALG_1:def 16;
assume A2:
U1,U2 are_similar
; for o being OperSymbol of (MSSign U1) holds Den o,((MSAlg U2) Over (MSSign U1)) is operation of U2
then A3:
MSSign U1 = MSSign U2
by Th10;
let o be OperSymbol of (MSSign U1); Den o,((MSAlg U2) Over (MSSign U1)) is operation of U2
A4: Den o,((MSAlg U2) Over (MSSign U1)) =
the Charact of ((MSAlg U2) Over (MSSign U1)) . o
by MSUALG_1:def 11
.=
(MSCharact U2) . o
by A3, A1, Th9
.=
the charact of U2 . o
by MSUALG_1:def 15
;
reconsider f = (*--> 0 ) * (signature U1) as Function of (dom (signature U1)),({0 } * ) by MSUALG_1:7;
A5:
dom (signature U1) = dom the charact of U1
by Lm1;
signature U1 = signature U2
by A2, UNIALG_2:def 2;
then
( the carrier' of (MSSign U1) = dom (signature U1) & dom the charact of U1 = dom the charact of U2 )
by A5, Lm1, MSUALG_1:def 13;
hence
Den o,((MSAlg U2) Over (MSSign U1)) is operation of U2
by A4, A5, FUNCT_1:def 5; verum