let S, T be complete Scott TopLattice; :: thesis: for f being Function of S,T st S is algebraic & T is algebraic holds
( f is continuous iff for x being Element of S
for k being Element of T st k in the carrier of (CompactSublatt T) holds
( k <= f . x iff ex j being Element of S st
( j in the carrier of (CompactSublatt S) & j <= x & k <= f . j ) ) )
let f be Function of S,T; :: thesis: ( S is algebraic & T is algebraic implies ( f is continuous iff for x being Element of S
for k being Element of T st k in the carrier of (CompactSublatt T) holds
( k <= f . x iff ex j being Element of S st
( j in the carrier of (CompactSublatt S) & j <= x & k <= f . j ) ) ) )
assume that
A1: S is algebraic and
A2: T is algebraic ; :: thesis: ( f is continuous iff for x being Element of S
for k being Element of T st k in the carrier of (CompactSublatt T) holds
( k <= f . x iff ex j being Element of S st
( j in the carrier of (CompactSublatt S) & j <= x & k <= f . j ) ) )
A3: S is continuous by A1, WAYBEL_8:7;
A4: T is continuous by A2, WAYBEL_8:7;
assume for x being Element of S
for k being Element of T st k in the carrier of (CompactSublatt T) holds
( k <= f . x iff ex j being Element of S st
( j in the carrier of (CompactSublatt S) & j <= x & k <= f . j ) ) ; :: thesis: f is continuous
then for x being Element of S
for y being Element of T holds
( y << f . x iff ex w being Element of S st
( w << x & y << f . w ) ) by A2, Lm18;
hence f is continuous by A3, A4, Th23; :: thesis: verum