let S be RealNormSpace; :: thesis: for f being PartFunc of REAL, the carrier of S st ex r being Point of S st rng f = {r} holds
f is continuous

let f be PartFunc of REAL, the carrier of S; :: thesis: ( ex r being Point of S st rng f = {r} implies f is continuous )
given r being Point of S such that A1: rng f = {r} ; :: thesis: f is continuous
now :: thesis: for x1, x2 being Real st x1 in dom f & x2 in dom f holds
||.((f /. x1) - (f /. x2)).|| <= 1 * |.(x1 - x2).|
let x1, x2 be Real; :: thesis: ( x1 in dom f & x2 in dom f implies ||.((f /. x1) - (f /. x2)).|| <= 1 * |.(x1 - x2).| )
assume A2: ( x1 in dom f & x2 in dom f ) ; :: thesis: ||.((f /. x1) - (f /. x2)).|| <= 1 * |.(x1 - x2).|
then f . x2 in rng f by FUNCT_1:def 3;
then f /. x2 in rng f by ;
then A3: f /. x2 = r by ;
f . x1 in rng f by ;
then f /. x1 in rng f by ;
then f /. x1 = r by ;
then ||.((f /. x1) - (f /. x2)).|| = 0 by ;
hence ||.((f /. x1) - (f /. x2)).|| <= 1 * |.(x1 - x2).| by COMPLEX1:46; :: thesis: verum
end;
then f is Lipschitzian ;
hence f is continuous ; :: thesis: verum