let G be _Graph; :: thesis: for W being Walk of G
for m, n being odd Element of NAT st m <= n & n <= len W & W . m = W . n holds
len (W .remove m,n) = ((len W) + m) - n
let W be Walk of G; :: thesis: for m, n being odd Element of NAT st m <= n & n <= len W & W . m = W . n holds
len (W .remove m,n) = ((len W) + m) - n
let m, n be odd Element of NAT ; :: thesis: ( m <= n & n <= len W & W . m = W . n implies len (W .remove m,n) = ((len W) + m) - n )
assume that
A1: m <= n and
A2: n <= len W and
A3: W . m = W . n ; :: thesis: len (W .remove m,n) = ((len W) + m) - n
(len (W .remove m,n)) + n = (len W) + m by A1, A2, A3, Lm24;
hence len (W .remove m,n) = ((len W) + m) - n ; :: thesis: verum