fact: Definition mule_subdef x y := match x, y with | x%:E , y%:E => (x * y)%:E | -oo, y | y, -oo => if y == 0 then 0 else if 0 < y then -oo else +oo | +oo, y | y, +oo => if y == 0 then 0 else if 0 < y then +oo else -oo end.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed