Issues with MathQuill and answers comparing to the string "infinity"

[dlglin]

This was motivated by Library/Utah/Calculus_II/set6_Indeterminate_Forms_and_Improper_Integrals/set6_pr3.pg.

If a problem is coded to explicitly look for the string "infinity" (for example using str_cmp) and MathQuill is enabled, then students get some counterintuitive behaviour. When they start typing the word infinity, they get to inf and it is replaced with the infinity symbol. In such a circumstance if they submit their answer it is marked wrong because MQ submits the string "inf". This is not an issue with MathObjects since "inf" is an alias for "infinity" in the Numeric context.

There are some workarounds, such as instructing students to use the text mode in MQ, typing "INFINITY" in all caps or continuing to type the word infinity despite the substitution (i.e. "∞inity" is marked right), but the right approach is to convert these questions to MathObjects and work on eliminating str_cmp (and other outdated answer checkers) from the OPL.

I'm going to poke around the OPL to see if I can find which problems have this issue, but it's not just a simple grep since "infinity" could be stored in a variable on a different line. I'll post what I find here.