is mentioned by

Thm* x,y:, n:. ((x+y) rem n) = (((x rem n)+(y rem n)) rem n)+if (x+y < 0)(0 < (((x rem n)+(y rem n)) rem n))-|n| ;((((x rem n)+(y rem n)) rem n) < 0)(0 < x+y)|n| else 0 fi	[rem_add]
Thm* i:. f91(i) ~ if 101 < i i-10 else 91 fi	[f91-val]
Def f91(i) == if 100 < i i-10 else f91(f91(i+11)) fi (recursive)	[f91]
Def upto(i;j) == if i < j [i / upto(i+1;j)] else nil fi (recursive)	[upto]

In prior sections: bool 1 sqequal 1 list 1 mb nat mb list 1

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