let A, B, C, D be real number ; :: thesis: for h being Function of (TOP-REAL 2),(TOP-REAL 2) st A > 0 & C > 0 & h = AffineMap A,B,C,D holds
( h is being_homeomorphism & ( for p1, p2 being Point of (TOP-REAL 2) st p1 `2 < p2 `2 holds
(h . p1) `2 < (h . p2) `2 ) )
let h be Function of (TOP-REAL 2),(TOP-REAL 2); :: thesis: ( A > 0 & C > 0 & h = AffineMap A,B,C,D implies ( h is being_homeomorphism & ( for p1, p2 being Point of (TOP-REAL 2) st p1 `2 < p2 `2 holds
(h . p1) `2 < (h . p2) `2 ) ) )
assume A1:
( A > 0 & C > 0 & h = AffineMap A,B,C,D )
; :: thesis: ( h is being_homeomorphism & ( for p1, p2 being Point of (TOP-REAL 2) st p1 `2 < p2 `2 holds
(h . p1) `2 < (h . p2) `2 ) )
then A2:
h is one-to-one
by JGRAPH_2:54;
A3:
dom h = [#] (TOP-REAL 2)
by FUNCT_2:def 1;
set g = AffineMap (1 / A),(- (B / A)),(1 / C),(- (D / C));
A4:
dom (AffineMap (1 / A),(- (B / A)),(1 / C),(- (D / C))) = [#] (TOP-REAL 2)
by FUNCT_2:def 1;
A5:
AffineMap (1 / A),(- (B / A)),(1 / C),(- (D / C)) = h "
by A1, Th49;
then A6:
rng h = [#] (TOP-REAL 2)
by A2, A4, FUNCT_1:54;
then A7:
h /" is continuous
by A1, A5, JGRAPH_2:54, TOPS_2:def 4;
for p1, p2 being Point of (TOP-REAL 2) st p1 `2 < p2 `2 holds
(h . p1) `2 < (h . p2) `2
proof
let p1,
p2 be
Point of
(TOP-REAL 2);
:: thesis: ( p1 `2 < p2 `2 implies (h . p1) `2 < (h . p2) `2 )
assume A8:
p1 `2 < p2 `2
;
:: thesis: (h . p1) `2 < (h . p2) `2
A9:
h . p1 = |[((A * (p1 `1 )) + B),((C * (p1 `2 )) + D)]|
by A1, JGRAPH_2:def 2;
A10:
h . p2 = |[((A * (p2 `1 )) + B),((C * (p2 `2 )) + D)]|
by A1, JGRAPH_2:def 2;
A11:
(h . p1) `2 = (C * (p1 `2 )) + D
by A9, EUCLID:56;
A12:
(h . p2) `2 = (C * (p2 `2 )) + D
by A10, EUCLID:56;
C * (p1 `2 ) < C * (p2 `2 )
by A1, A8, XREAL_1:70;
hence
(h . p1) `2 < (h . p2) `2
by A11, A12, XREAL_1:10;
:: thesis: verum
end;
hence
( h is being_homeomorphism & ( for p1, p2 being Point of (TOP-REAL 2) st p1 `2 < p2 `2 holds
(h . p1) `2 < (h . p2) `2 ) )
by A1, A2, A3, A6, A7, TOPS_2:def 5; :: thesis: verum