Part 5
More Properties of the Part_btwn()

2. Removal of a substring with the starting position zero, and ending position equal to or greater than the length of the original string produces the original non-empty string.

m, n : Ν;
if n ≥ | α | then Prt_btwn (0, n, α) = α and
Prt_btwn (m, n, α) = α ≠ Λ then m = 0 and n ≥ | α |;

Example:
β = < 7, 4, 8>; n = 4;
Prt_btwn (0, 4, β ) = β = <7, 4, 8> ≠ Λ,
then we know that the starting position was 0 and n ≥ | β |;