let p be Point of (TOP-REAL 2); for i being Nat
for f being S-Sequence_in_R2 st p in LSeg (f,i) & not p in rng f holds
Ins (f,i,p) is being_S-Seq
let i be Nat; for f being S-Sequence_in_R2 st p in LSeg (f,i) & not p in rng f holds
Ins (f,i,p) is being_S-Seq
let f be S-Sequence_in_R2; ( p in LSeg (f,i) & not p in rng f implies Ins (f,i,p) is being_S-Seq )
assume that
A1:
p in LSeg (f,i)
and
A2:
not p in rng f
; Ins (f,i,p) is being_S-Seq
set g = Ins (f,i,p);
thus
Ins (f,i,p) is one-to-one
by A2, FINSEQ_5:76; TOPREAL1:def 8 ( 2 <= len (Ins (f,i,p)) & Ins (f,i,p) is unfolded & Ins (f,i,p) is s.n.c. & Ins (f,i,p) is special )
len (Ins (f,i,p)) = (len f) + 1
by FINSEQ_5:69;
then A3:
len (Ins (f,i,p)) >= len f
by NAT_1:11;
len f >= 2
by TOPREAL1:def 8;
hence
len (Ins (f,i,p)) >= 2
by A3, XXREAL_0:2; ( Ins (f,i,p) is unfolded & Ins (f,i,p) is s.n.c. & Ins (f,i,p) is special )
thus
Ins (f,i,p) is unfolded
by A1, Th32; ( Ins (f,i,p) is s.n.c. & Ins (f,i,p) is special )
thus
Ins (f,i,p) is s.n.c.
by A1, A2, Th37; Ins (f,i,p) is special
thus
Ins (f,i,p) is special
by A1, Th41; verum