let f, g be FinSequence of (TOP-REAL 2); for p being Point of (TOP-REAL 2) st f . (len f) = g . 1 & p in L~ g & f is being_S-Seq & g is being_S-Seq & (L~ f) /\ (L~ g) = {(g . 1)} & p <> g . 1 holds
(mid (f,1,((len f) -' 1))) ^ (R_Cut (g,p)) is_S-Seq_joining f /. 1,p
let p be Point of (TOP-REAL 2); ( f . (len f) = g . 1 & p in L~ g & f is being_S-Seq & g is being_S-Seq & (L~ f) /\ (L~ g) = {(g . 1)} & p <> g . 1 implies (mid (f,1,((len f) -' 1))) ^ (R_Cut (g,p)) is_S-Seq_joining f /. 1,p )
assume that
A1:
f . (len f) = g . 1
and
A2:
p in L~ g
and
A3:
f is being_S-Seq
and
A4:
g is being_S-Seq
and
A5:
(L~ f) /\ (L~ g) = {(g . 1)}
and
A6:
p <> g . 1
; (mid (f,1,((len f) -' 1))) ^ (R_Cut (g,p)) is_S-Seq_joining f /. 1,p
len g >= 2
by A4, TOPREAL1:def 8;
then A7:
1 <= len g
by XXREAL_0:2;
R_Cut (g,p) is_S-Seq_joining g /. 1,p
by A2, A4, A6, Th32;
then A8:
(R_Cut (g,p)) . 1 = g /. 1
;
then A9:
(R_Cut (g,p)) . 1 = f . (len f)
by A1, A7, FINSEQ_4:15;
A10:
len f >= 2
by A3, TOPREAL1:def 8;
then A11:
1 <= len f
by XXREAL_0:2;
A12:
(1 + 1) - 1 <= (len f) - 1
by A10, XREAL_1:9;
A13:
((len f) -' 1) + 1 = len f
by A10, XREAL_1:235, XXREAL_0:2;
then
f /. (len f) in LSeg ((f /. ((len f) -' 1)),(f /. (((len f) -' 1) + 1)))
by RLTOPSP1:68;
then
f /. (len f) in LSeg (f,((len f) -' 1))
by A12, A13, TOPREAL1:def 3;
then
f . (len f) in LSeg (f,((len f) -' 1))
by A11, FINSEQ_4:15;
then A14:
f . (len f) in L~ f
by SPPOL_2:17;
A15:
R_Cut (g,p) is being_S-Seq
by A2, A4, A6, Th35;
then A16:
1 + 1 <= len (R_Cut (g,p))
by TOPREAL1:def 8;
then A17:
1 <= len (R_Cut (g,p))
by XXREAL_0:2;
then
(R_Cut (g,p)) . (len (R_Cut (g,p))) = (R_Cut (g,p)) /. (len (R_Cut (g,p)))
by FINSEQ_4:15;
then A18:
(R_Cut (g,p)) /. (len (R_Cut (g,p))) = p
by A2, Th24;
(R_Cut (g,p)) /. 1 in LSeg (((R_Cut (g,p)) /. 1),((R_Cut (g,p)) /. (1 + 1)))
by RLTOPSP1:68;
then
(R_Cut (g,p)) . 1 in LSeg (((R_Cut (g,p)) /. 1),((R_Cut (g,p)) /. (1 + 1)))
by A17, FINSEQ_4:15;
then
(R_Cut (g,p)) . 1 in LSeg ((R_Cut (g,p)),1)
by A16, TOPREAL1:def 3;
then
g /. 1 in L~ (R_Cut (g,p))
by A8, SPPOL_2:17;
then
g . 1 in L~ (R_Cut (g,p))
by A7, FINSEQ_4:15;
then
f . (len f) in (L~ f) /\ (L~ (R_Cut (g,p)))
by A1, A14, XBOOLE_0:def 4;
then A19:
{(f . (len f))} c= (L~ f) /\ (L~ (R_Cut (g,p)))
by ZFMISC_1:31;
L~ (R_Cut (g,p)) c= L~ g
by A2, Th41;
then
(L~ f) /\ (L~ (R_Cut (g,p))) c= (L~ f) /\ (L~ g)
by XBOOLE_1:27;
then
(L~ f) /\ (L~ (R_Cut (g,p))) = {((R_Cut (g,p)) . 1)}
by A1, A5, A9, A19, XBOOLE_0:def 10;
hence
(mid (f,1,((len f) -' 1))) ^ (R_Cut (g,p)) is_S-Seq_joining f /. 1,p
by A3, A15, A9, A18, Th46; verum