let X be set ; for f1, f2 being PartFunc of REAL,REAL st X c= (dom f1) /\ (dom f2) & f1 | X is continuous & f1 " {0} = {} & f2 | X is continuous holds
(f2 / f1) | X is continuous
let f1, f2 be PartFunc of REAL,REAL; ( X c= (dom f1) /\ (dom f2) & f1 | X is continuous & f1 " {0} = {} & f2 | X is continuous implies (f2 / f1) | X is continuous )
assume A1:
X c= (dom f1) /\ (dom f2)
; ( not f1 | X is continuous or not f1 " {0} = {} or not f2 | X is continuous or (f2 / f1) | X is continuous )
assume that
A2:
f1 | X is continuous
and
A3:
f1 " {0} = {}
and
A4:
f2 | X is continuous
; (f2 / f1) | X is continuous
A5: dom (f1 ^) =
(dom f1) \ {}
by A3, RFUNCT_1:def 2
.=
dom f1
;
(f1 ^) | X is continuous
by A2, A3, Th22;
then
(f2 (#) (f1 ^)) | X is continuous
by A1, A4, A5, Th18;
hence
(f2 / f1) | X is continuous
by RFUNCT_1:31; verum