let C be non empty set ; :: thesis: for f1, f2 being PartFunc of C,COMPLEX
for r being Element of COMPLEX holds r (#) (f1 - f2) = (r (#) f1) - (r (#) f2)
let f1, f2 be PartFunc of C,COMPLEX; :: thesis: for r being Element of COMPLEX holds r (#) (f1 - f2) = (r (#) f1) - (r (#) f2)
let r be Element of COMPLEX ; :: thesis: r (#) (f1 - f2) = (r (#) f1) - (r (#) f2)
A1: dom (r (#) (f1 - f2)) = dom (f1 - f2) by Th7
.= (dom f1) /\ (dom f2) by Th4
.= (dom f1) /\ (dom (r (#) f2)) by Th7
.= (dom (r (#) f1)) /\ (dom (r (#) f2)) by Th7
.= dom ((r (#) f1) - (r (#) f2)) by Th4 ;

now

let c be Element of C; :: thesis: ( c in dom (r (#) (f1 - f2)) implies (r (#) (f1 - f2)) /. c = ((r (#) f1) - (r (#) f2)) /. c )
assume A2: c in dom (r (#) (f1 - f2)) ; :: thesis: (r (#) (f1 - f2)) /. c = ((r (#) f1) - (r (#) f2)) /. c
then A3: c in dom (f1 - f2) by Th7;
A4: c in (dom (r (#) f1)) /\ (dom (r (#) f2)) by A1, A2, Th4;
then A5: c in dom (r (#) f1) by XBOOLE_0:def 4;
A6: c in dom (r (#) f2) by A4, XBOOLE_0:def 4;
thus (r (#) (f1 - f2)) /. c = r * ((f1 - f2) /. c) by A2, Th7
.= r * ((f1 /. c) - (f2 /. c)) by A3, Th4
.= (r * (f1 /. c)) - (r * (f2 /. c))
.= ((r (#) f1) /. c) - (r * (f2 /. c)) by A5, Th7
.= ((r (#) f1) /. c) - ((r (#) f2) /. c) by A6, Th7
.= ((r (#) f1) - (r (#) f2)) /. c by A1, A2, Th4 ; :: thesis: verum

end;

hence r (#) (f1 - f2) = (r (#) f1) - (r (#) f2) by A1, PARTFUN2:1; :: thesis: verum