Knowability
Ben Brubaker, Daniel Bump, Solomon Friedberg · Princeton University Press eBooks · 2011
This chapter introduces the Knowability Lemma, which explains when products of Gauss sums associated to elements of a preaccordion are explicitly evaluable as polynomials in q, the order of the residue class field. It considers an episode in the cartoon associated to the short Gelfand-Tsetlin pattern and the three cases that apply according to the Knowability Lemma, two of which are maximality and knowability. Knowability is not important for the proof that Statement C implies Statement B. The chapter discusses the cases where ε is Class II or Class I, leaving the remaining two cases to the reader. It also describes the variant of the argument for the case that ε is of Class I, again leaving the two other cases to the reader.