- Properties
- References
- Further reading
In algebra, the principal factor of a 
-class J of a semigroup S is equal to J if J is the kernel of S, and to 
otherwise.
Properties
- A principal factor is a simple, 0-simple or null semigroup.[1]
References
1. ^Grillet (1995), p. 50, Proposition 4.9.
Further reading
- {{citation|last= Howie|first= John M.|authorlink=John Mackintosh Howie|title=Fundamentals of Semigroup Theory|year=1995|publisher=Clarendon Press|isbn=0-19-851194-9}}.
- {{citation|title=The algebraic theory of semigroups, volume 1|first1=A. H.|last1=Clifford|authorlink1= Alfred H. Clifford |first2=G. B.|last2=Preston|authorlink2=Gordon Preston|publisher=American Mathematical Society|year=1961}}.
- {{citation|last=Grillet|first=P. A.|title=Semigroups: An Introduction to the Structure Theory|year=1995|publisher=Marcel Dekker|page=49|isbn=0824796624}}.
1 : Semigroup theory