let X be RealBanachSpace; :: thesis: for Z being open Subset of REAL
for a, b being Real
for y0 being VECTOR of X
for G being Function of X,X
for y being continuous PartFunc of REAL, the carrier of X st a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) holds
y is_a_fixpoint_of Fredholm (G,a,b,y0)

let Z be open Subset of REAL; :: thesis: for a, b being Real
for y0 being VECTOR of X
for G being Function of X,X
for y being continuous PartFunc of REAL, the carrier of X st a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) holds
y is_a_fixpoint_of Fredholm (G,a,b,y0)

let a, b be Real; :: thesis: for y0 being VECTOR of X
for G being Function of X,X
for y being continuous PartFunc of REAL, the carrier of X st a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) holds
y is_a_fixpoint_of Fredholm (G,a,b,y0)

let y0 be VECTOR of X; :: thesis: for G being Function of X,X
for y being continuous PartFunc of REAL, the carrier of X st a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) holds
y is_a_fixpoint_of Fredholm (G,a,b,y0)

let G be Function of X,X; :: thesis: for y being continuous PartFunc of REAL, the carrier of X st a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) holds
y is_a_fixpoint_of Fredholm (G,a,b,y0)

let y be continuous PartFunc of REAL, the carrier of X; :: thesis: ( a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) implies y is_a_fixpoint_of Fredholm (G,a,b,y0) )

assume A1: ( a < b & Z = ].a,b.[ & G is_Lipschitzian_on the carrier of X & dom y = ['a,b'] & y is_differentiable_on Z & y /. a = y0 & ( for t being Real st t in Z holds
diff (y,t) = G . (y /. t) ) ) ; :: thesis: y is_a_fixpoint_of Fredholm (G,a,b,y0)
X1: ['a,b'] = [.a,b.] by ;
A2: dom (Fredholm (G,a,b,y0)) = the carrier of () by FUNCT_2:def 1;
A3: y is Element of the carrier of () by ;
X2: dom G = the carrier of X by FUNCT_2:def 1;
then G is_continuous_on dom G by ;
then consider f, g, Gf being continuous PartFunc of REAL, the carrier of X such that
A5: ( y = f & (Fredholm (G,a,b,y0)) . y = g & dom f = ['a,b'] & dom g = ['a,b'] & Gf = G * f & ( for t being Real st t in ['a,b'] holds
g /. t = y0 + (integral (Gf,a,t)) ) ) by Def8, A1, A3;
rng f c= dom G by X2;
then A6: dom (G * f) = ['a,b'] by ;
for t being Real st t in Z holds
diff (y,t) = Gf /. t
proof
let t be Real; :: thesis: ( t in Z implies diff (y,t) = Gf /. t )
assume A7: t in Z ; :: thesis: diff (y,t) = Gf /. t
hence diff (y,t) = G . (y /. t) by A1
.= G . (y . t) by
.= Gf . t by
.= Gf /. t by ;
:: thesis: verum
end;
hence y is_a_fixpoint_of Fredholm (G,a,b,y0) by ; :: thesis: verum