Question: reliable mark symbolic answers

The forum is on "How do I ...", and my question is

"How do I get MapleTA to be reliable in marking symbolic answers?"

It is OK at marking wrong answers wrong. The difficulty I'm having is that too many equivalent correct answers are also marked wrong.

The class sizes are around 500 students, and it is very tedious checking their grumbles about mismarking.

Examples:

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I had an instance, using MapleSoft's IntroToCalcUnit1 questions, where

 abs(3*x-24) was marked correct while 3*abs(x-8) is marked wrong.

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Today, I've had a student (using MapleSoft's IntroToCalcUnit2 questions) being drilled on differentiation, being mismarked, in that the "Your answer" was marked wrong.

Find the derivative of
f(x)=-cos(2*x - 4)/sin(2*x - 1)

Your Answer :  2*cos(3)/sin(1-2 x)^2

GK Comment : mapleta's  "correct answer", found using the chain rule, is a longer, less simplified answer. BOTH are correct.

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In the MapleSoft's IntroToCalcUnit4 questions on integration by substitution in the current version only one of the umpteen alternative substitutions gets marked correct (but, at least I can see how to re-code this one, asking for a monic polynomial to make the answer unique).

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I think this difficulty, which all of us will be suffering, requires more than just fixing the code one question at a time. In AiM, another maple-based Computer Aided Assessment system in which the maple underpinnings have been in use since the 1980s (i.e. from before the Web even), there is a Test/Symbolic function that is useful for recognizing equivalent forms of answers.

THIS POST IS HERE TO TRY TO GET mapleTA DEVELOPERS TO IMPROVE THE CODE.

Regards (and Best Wishes, etc., etc.), Grant Keady