There is a publishing company called Springer that uses chess knight for its symbol. Springer is a German publishing company, founded in the late 1800's, that publishes scientific textbooks and technical journals. This maybe something that inspired Pynchon (or at least something he came across before writing GR) considering his techinical writing backround. The headquarters was in Berlin, but was destroyed during the WW2. Being the most prominant German scientific publisher any of the German scientists in the novel would surely have been familiar with it.