set G = CutLastLoc F;
per cases
( CutLastLoc F is empty or not CutLastLoc F is empty )
;
suppose
not
CutLastLoc F is
empty
;
CutLastLoc F is initial then reconsider G =
CutLastLoc F as non
empty finite Function ;
G is
initial
proof
let m,
l be
Nat;
AFINSQ_1:def 13 ( l in dom G & m < l implies m in dom G )
assume that A1:
l in dom G
and A2:
m < l
;
m in dom G
set M =
dom F;
reconsider R =
{[(LastLoc F),(F . (LastLoc F))]} as
Relation ;
R = (LastLoc F) .--> (F . (LastLoc F))
by FUNCT_4:87;
then A5:
dom R = {(LastLoc F)}
by FUNCOP_1:19;
then A6:
(dom F) \ (dom R) = dom G
by VALUED_1:37;
then
l in dom F
by A1, XBOOLE_0:def 5;
then A7:
m in dom F
by A2, Def13;
l in dom F
by A6, A1, XBOOLE_0:def 5;
then
m <> LastLoc F
by A2, XXREAL_2:def 8;
then
not
m in {(LastLoc F)}
by TARSKI:def 1;
hence
m in dom G
by A5, A6, A7, XBOOLE_0:def 5;
verum
end; hence
CutLastLoc F is
initial
;
verum end; end;