let x be set ; for U being non empty set
for f being Function
for R being total reflexive Relation of U st x in dom f & f is U -valued holds
f is id {x},R -respecting
let U be non empty set ; for f being Function
for R being total reflexive Relation of U st x in dom f & f is U -valued holds
f is id {x},R -respecting
let f be Function; for R being total reflexive Relation of U st x in dom f & f is U -valued holds
f is id {x},R -respecting
let R be total reflexive Relation of U; ( x in dom f & f is U -valued implies f is id {x},R -respecting )
set E = id {x};
assume A1:
x in dom f
; ( not f is U -valued or f is id {x},R -respecting )
then reconsider D = dom f as non empty set ;
(id {x}) \+\ {[x,x]} = {}
;
then A2:
id {x} = {[x,x]}
by FOMODEL0:29;
reconsider xx = x as Element of D by A1;
assume
f is U -valued
; f is id {x},R -respecting
then
rng f c= U
by RELAT_1:def 19;
then reconsider ff = f as Function of D,U by FUNCT_2:2;
now for x1, x2 being set st [x1,x2] in id {x} holds
[(f . x1),(f . x2)] in Rlet x1,
x2 be
set ;
( [x1,x2] in id {x} implies [(f . x1),(f . x2)] in R )assume
[x1,x2] in id {x}
;
[(f . x1),(f . x2)] in Rthen
[x1,x2] = [x,x]
by A2, TARSKI:def 1;
then A3:
(
x1 = x &
x2 = x )
by XTUPLE_0:1;
(
f . xx = f . xx &
ff . xx in U )
;
hence
[(f . x1),(f . x2)] in R
by EQREL_1:5, A3;
verum end;
hence
f is id {x},R -respecting
; verum