Function vstd::arithmetic::div_mod::lemma_indistinguishable_quotients
source · pub broadcast proof fn lemma_indistinguishable_quotients(a: int, b: int, d: int)
Expand description
requires
0 < d,
0 <= a - a % d <= b < a + d - a % d,
ensuresa / d == b / d,
Proof that for a positive integer d
, if a - a % d
is less than
or equal to b
and b
is less than a + d - a % d
, then the
quotient of a
divided by d
is equivalent to the quotient of
b
divided by d
.
In other words, if a
and b
occur between the same two
multiples of d
, then their quotient with d
is equivalent.