idempotent

Recall that a matrix A in [M.sub.n](L) is called idempotent if [A.sup.2] = A.

Let S be a regular semigroup with set E(S) of idempotent elements.

Contrary to the orthogonal projection is idempotent and Hermitian, the oblique one is idempotent and not Hermitian.

Since the mapping [sigma] is idempotent, [sigma]([empty set]) = S and [sigma]([H.sub.1] [union] [H.sub.2]) = [sigma]([H.sub.1]) [intersection] [sigma]([H.sub.2]) for all [H.sub.1], [H.sub.2] [member of] S, the proof is clear.

Let t be the smallest positive integer for which [r.sup.t] is idempotent for every r [member of] [R.sub.c] and the exponent of G divides t.

If e is an idempotent of T and [f.sup.-1](e) is nonempty then [f.sup.-1](e) is an inverse sub semigroup of S.

In particular, they are idempotent and they follow the semi-group absorption law, i.e., [for all] n [greater than or equal to] m [greater than or equal to] 0,we have

Now we have the fact that for any idempotent e, d(y(1 - e))e = -y(1 - e)d(e), ed(e)e = 0 and so

The time series of discriminants (dsk [M.sub.n]), discriminant coefficients (dskCoeff [M.sub.n]) and idempotent coefficients (IdeCoeff [M.sub.n]) are calculated from two time series: duration of RR interval taken from the II standard lead and duration of JT interval of the V standard lead.