let n be Element of NAT ; :: thesis: for P1, P being Subset of
for Q being Subset of
for p1, p2 being Point of st P1 is_an_arc_of p1,p2 & P1 c= P & Q = P1 \ {p1,p2} holds
Q is connected
let P1, P be Subset of ; :: thesis: for Q being Subset of
for p1, p2 being Point of st P1 is_an_arc_of p1,p2 & P1 c= P & Q = P1 \ {p1,p2} holds
Q is connected
let Q be Subset of ; :: thesis: for p1, p2 being Point of st P1 is_an_arc_of p1,p2 & P1 c= P & Q = P1 \ {p1,p2} holds
Q is connected
let p1, p2 be Point of ; :: thesis: ( P1 is_an_arc_of p1,p2 & P1 c= P & Q = P1 \ {p1,p2} implies Q is connected )
assume that
A1: P1 is_an_arc_of p1,p2 and
A2: P1 c= P and
A3: Q = P1 \ {p1,p2} ; :: thesis: Q is connected
[#] ((TOP-REAL n) | P1) = P1 by PRE_TOPC:def 10;
then reconsider Q' = Q as Subset of by A3, XBOOLE_1:36;
Q' is connected by A1, A3, Th53;
hence Q is connected by A2, Th54; :: thesis: verum