English
For a,b,c nonzero with a ≤ c, one has c = a + spanSingleton(c.divMod b a)·b; i.e., the division with remainder exists as a single principal correction.
Русский
Для ненулевых a,b,c с a ≤ c имеем c = a + spanSingleton(c.divMod b a)·b; т.е. разложение по частям через 'остаток'.
LaTeX
$$$c = a + \operatorname{spanSingleton}(c.divMod\, b\, a) \cdot b$ при условиях $a\le c$, $a\neq 0$, $b\neq 0$.$$
Lean4
theorem divMod_spec {a b c : FractionalIdeal R⁰ K} (hac : a ≤ c) (ha : a ≠ 0) (hb : b ≠ 0) :
a + spanSingleton R⁰ (c.divMod b a) * b = c :=
by
rw [divMod, dif_pos ⟨hac, ha, hb⟩]
exact (IsDedekindDomain.exists_add_spanSingleton_mul_eq hac ha hb).choose_spec