1) Field theory 
[algebra] ==Properties== The Stufe s(F) is related to the Pythagoras number p(F) by p(F) ≤ s(F)+1. If F is not formally real then s(F) ≤ p(F) ≤ s(F)+1. The additive order of the form (1), and hence the exponent of the Witt group of F is equal to 2s(F). ==Examples== ...