Gauss content lemma: Let RR be a . For f,gR[x]f,g\in R[x] in the , choose generators c(f),c(g),c(fg)c(f),c(g),c(fg) of their coefficient ideals. Then

c(fg)  c(f)c(g),c(fg)\ \sim\ c(f)c(g),

where \sim denotes equality up to . Equivalently, the product of two is primitive.

Remarks

This lemma is the technical engine behind Gauss-type transfer results between R[x]R[x] and Frac(R)[x]\mathrm{Frac}(R)[x].