 activity on the part of
            at least one performer (see <a
            href="./actor-vocab.html#performedBy">#$performedBy).</a>
            Solving a math problem, planning an attack, performing a
            thought experiment are all examples of <a
            href="./doing-vocab.html#PurposefulMentalActivity">#$PurposefulMentalActivity.</a>
            However, daydreaming or having undesired obsessive thoughts
            are not examples. A borderline example might be arriving at
            