- #1
mnb96
- 715
- 5
If I have a semigroup S, is it possible to partition the set of element S into two semigroups [tex]S_1[/tex] and [tex]S_2[/tex] (with [tex]S_1 \cap S_2 = 0[/tex]), in such a way that [tex]S_1[/tex] has an identity element but [tex]S_2[/tex] has none?