I'm working on an assignment in my Theory of Computation course and have stumbled on a symbol I can't find an explanation for. The question is as follows:
Let $T = \{\langle M\rangle | M $ is a Turing Machine that accepts $w^{\scr R}$ whenever it accepts $w$.$\} $ Show that $T$ is undecidable.
The use of $\scr R$ is confusing, as I have never seen it mentioned in the text and can't find anything on this site or any other. Has anyone seen this use of the symbol before?
It is probably just word reversal. $$ aab^R = baa $$