If ab = a bεR (1)
There exists a′
εR, a′≠ 0 such that:
a′
b = 0 [1] (2)
And recall that, the principal ideal I = ‹a› is S2 ideal of R if, and only if the following
holds:
If ab = a bεR, b ≠ 1 (3)
There exists a′εR, a′
≠0 such that:
a′b = a′
a [2] (4)
In this work we use,
ann(a) = { xεR : ax = 0 }