An element $a$ of an <integral domain> is an <irreducible element> when it is nonzero and not a <unit>, and any <factorization> $a=bc$ has at least one <unit> factor. The exclusions of zero and <units> are part of the definition.

Solution

Past exam of the algebra, analysis and differential equations II course of the University of Oxford / 2006 / Algebra / 3 / a / Solution

 Solution (source code)