how to lame a horse by D (sD, or vD) ? Lame/bridge/blocking pieces are reality world, as there are trillions objects and ppl crowding everywhere. So, lame/block/ bridgeing gadgets are realities that are very useful. It could train brain complicated way.
=== Another reason is, lame/block pieces are long-playable, tactics heavy. Un-lamed pieces are easier to get draw games, and soon drains off all pieces energies. But lamed /bridged pieces could embed more artful maneuvrings of board locatiions and much more tactical and longer playable.
=== Thanks so much for your aid. Sincerely, Adella.
=========@ Mr. H.G.Muller
Dear respected H.G.Muller,