English
In a principal ideal domain that is a domain, if a ≠ 0 and b is a factor of a, then b ≠ 0.
Русский
В областьном кольце с первым принципом, если a ≠ 0 и b делит a, то b ≠ 0.
LaTeX
$$$a \neq 0 \\\\Rightarrow b \\\\in \\\\text{factors}(a) \\\\Rightarrow b \\\\neq 0$$$
Lean4
/-- Any Bézout domain is a GCD domain. This is not an instance since `GCDMonoid` contains data,
and this might not be how we would like to construct it. -/
noncomputable def toGCDDomain [IsBezout R] [IsDomain R] [DecidableEq R] : GCDMonoid R :=
gcdMonoidOfGCD (gcd · ·) (gcd_dvd_left · ·) (gcd_dvd_right · ·) dvd_gcd