In article <email@example.com>, WM <firstname.lastname@example.org> wrote:
> There exist > m, n, a b in |N, such that m is in FISON(a) and not in FIDSON(b) and n > is in FISON(b) and not in FISON(a).
For each natural n in |N, FISON(n) is defined to be the set of all naturals less than or equal to n. Thus n in FISON(m) if and only if n <= m, and similarly n NOT in FISON(m) if and only if m < n. If m is in FISON(a) and not in FISON(b), then b <= m < a if n is in FISON(b) and not in FISON(a), then a <= n < b
Thus in WM's world one must have b < a and a < b simultaneously. --