Question: total derivative, definition of variables,

Hey,

i am completely new in working with Maple. I spent the past 2 days to find a solution to my problem, but wasnt successfull.

Here is what i wanna do:

i have a function with 3 Variables and i wanna take the total derivative of this function.

Then i wanna know if the derivative is positiv or negative.

The only thing about the variables i know is that 2 of them are between 0 and 1, and the other variable can take any positiv value. So Maple should compute the results for all possible values and then tell me if it is positiv or negative, and for which values of the variables the derivative is positiv or negative.

I want Maple to tell for which variables the derivative is positiv, something like a>0.5 and b>0.2...

So basically the problems i have are...

1)how to define a variable like 0<a<1

2)how to take the total derivative

3)how to find out the values for which the total derivative is positive

Thanks