[Maxima-discuss] semantics of is(equal(a, b))

[Rubey, M. <mar...@tu...>]

Dear Maxima!

I wonder what the (intended) semantics of is(equal(a, b)) are.

I found https://maxima.sourceforge.io/docs/manual/Maxima_0027s-Database.html#equal, which, by way of example, states that

(%i8) is (equal (x, y));
(%o8)                        unknown

I would have expected false.  So, perhaps more precisely, when should is(equal(a, b)) return false?

OK, maybe I figured it out now:

    is(equal(a, b)) returns true (or false) if and only if a and b are equal (or not equal) for all possible values of their variables, as determined by evaluating ratsimp(a - b);

Does this mean that is(equal(a, b)) is false if and only if the function (a, b) \mapsto a-b does not have any zeros?

Best wishes,

Martin