let A be Euclidean preIfWhileAlgebra; :: thesis: for X being non empty countable set
for s being Element of Funcs (X,INT)
for T being Subset of (Funcs (X,INT))
for f being Euclidean ExecutionFunction of A, Funcs (X,INT),T
for x being Variable of f
for t being INT-Expression of A,f holds
( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

let X be non empty countable set ; :: thesis: for s being Element of Funcs (X,INT)
for T being Subset of (Funcs (X,INT))
for f being Euclidean ExecutionFunction of A, Funcs (X,INT),T
for x being Variable of f
for t being INT-Expression of A,f holds
( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

let s be Element of Funcs (X,INT); :: thesis: for T being Subset of (Funcs (X,INT))
for f being Euclidean ExecutionFunction of A, Funcs (X,INT),T
for x being Variable of f
for t being INT-Expression of A,f holds
( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

let T be Subset of (Funcs (X,INT)); :: thesis: for f being Euclidean ExecutionFunction of A, Funcs (X,INT),T
for x being Variable of f
for t being INT-Expression of A,f holds
( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

let f be Euclidean ExecutionFunction of A, Funcs (X,INT),T; :: thesis: for x being Variable of f
for t being INT-Expression of A,f holds
( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

let x be Variable of f; :: thesis: for t being INT-Expression of A,f holds
( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

let t be INT-Expression of A,f; :: thesis: ( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) )

(^ x) . s = x ;
hence ( (f . (s,(x := t))) . x = t . s & ( for z being Element of X st z <> x holds
(f . (s,(x := t))) . z = s . z ) ) by Th24; :: thesis: verum