is mentioned by

Thm* i,j:, F:({i..j}Prop). (k:{i..j}. Dec(F(k))) Dec(k:{i..j}. F(k))	[decidable__ex_int_seg]
Thm* a:, n:. q:. Div(a;n;q) & (a n) = q	[div_elim]
Def Rem(a;n;r) == q:. Div(a;n;q) & qn+r = a	[rem_nrel]

In prior sections: core

Try larger context: StandardLIB