let X, Y be set ; Y misses rng <:(X --> Y),(id X):>
set h = <:(X --> Y),(id X):>;
now for y being object holds
( not y in Y or not y in rng <:(X --> Y),(id X):> )given y being
object such that A1:
(
y in Y &
y in rng <:(X --> Y),(id X):> )
;
contradictionconsider x being
object such that A2:
(
x in dom <:(X --> Y),(id X):> &
y = <:(X --> Y),(id X):> . x )
by A1, FUNCT_1:def 3;
x in X
by A2, Lm8;
then A3:
y =
[Y,x]
by A2, Lm9
.=
{{Y,x},{Y}}
by TARSKI:def 5
;
A4:
{Y} in {{Y,x},{Y}}
by TARSKI:def 2;
Y in {Y}
by TARSKI:def 1;
hence
contradiction
by A1, A3, A4, XREGULAR:7;
verum end;
hence
Y misses rng <:(X --> Y),(id X):>
by XBOOLE_0:3; verum