Coprime elements of a unique factorization domain
= Coprime elements of a unique factorization domain
{title2=$\gcd(a,b)\in R^*$}
Two nonzero elements with no common nonunit irreducible factor. In a <unique factorization domain> this is equivalent to their greatest common divisor being a unit. Coprimality of numerator and denominator makes a fraction reduced, so simultaneous restrictions on its denominator can force it to be a <regular function>.