by BartTM on Fri Sep 27, 2013 2:23 pm
You may have removed the tick in the 'Problem is active on this site' box as well as the sandpit one.
I put them both back so it is in your sandpit again.
The problem could do with an introduction and a lot more variations, esp. to refute reasonable looking wrong moves.
It is a lot of work, but that is what makes these stand out from the book version where maybe just one or two wrong variations get shown.