let x be set ; :: thesis: for R1, R2 being Relation holds Im (R1 /\ R2),x = (Im R1,x) /\ (Im R2,x)
let R1, R2 be Relation; :: thesis: Im (R1 /\ R2),x = (Im R1,x) /\ (Im R2,x)
thus
Im (R1 /\ R2),x c= (Im R1,x) /\ (Im R2,x)
:: according to XBOOLE_0:def 10 :: thesis: (Im R1,x) /\ (Im R2,x) c= Im (R1 /\ R2),xproof
let y be
set ;
:: according to TARSKI:def 3 :: thesis: ( not y in Im (R1 /\ R2),x or y in (Im R1,x) /\ (Im R2,x) )
assume
y in Im (R1 /\ R2),
x
;
:: thesis: y in (Im R1,x) /\ (Im R2,x)
then A1:
[x,y] in R1 /\ R2
by Th9;
then A2:
[x,y] in R1
by XBOOLE_0:def 4;
A3:
[x,y] in R2
by A1, XBOOLE_0:def 4;
A4:
y in Im R1,
x
by A2, Th9;
y in Im R2,
x
by A3, Th9;
hence
y in (Im R1,x) /\ (Im R2,x)
by A4, XBOOLE_0:def 4;
:: thesis: verum
end;
let y be set ; :: according to TARSKI:def 3 :: thesis: ( not y in (Im R1,x) /\ (Im R2,x) or y in Im (R1 /\ R2),x )
assume A5:
y in (Im R1,x) /\ (Im R2,x)
; :: thesis: y in Im (R1 /\ R2),x
then A6:
y in Im R1,x
by XBOOLE_0:def 4;
A7:
y in Im R2,x
by A5, XBOOLE_0:def 4;
A8:
[x,y] in R1
by A6, Th9;
[x,y] in R2
by A7, Th9;
then
[x,y] in R1 /\ R2
by A8, XBOOLE_0:def 4;
hence
y in Im (R1 /\ R2),x
by Th9; :: thesis: verum