Since you don't give an example and most people will not have that book available, I think many will be able to answer this. Since this is posted under "Quantum Physics", and linear operators are often used there, without any more information I would suspect something line "adjoint" as in "ad T" is the adjoint of the operator T. Was "ad" used with an operator or just as a word on its own?Jimmy Snyder said:I'm reading QFT: Basics in Mathematics and Physics, by Eberhard Zeidler. Once in a while, in his proofs, I see the word (abbreviation?) Ad. For instance on page 375. The author is German and I suppose this imight be common practice in German texts. Does anyone here know what it means?
I'm sorry, I didn't realize that there were some people that don't have a copy of the book. It must stand for some kind of enumeration like case N, case R, etc. That's how it is used on page 375.my_wan said:I've seen it used as the prefix for an enumeration of the steps in a proof, but don't know what it stands for.