Custom proof environment

Question

How to define another proof environment, say, for the "Proof of lemma"? Also, how to make it without the qed box? (I need one with qed box, and another one without qed box.)

I'm using amsbook document class with amsthm package.

Answer 1

if you're using amsthm, you don't need another proof environment. the features you want are already built in.

to get a heading "Proof of lemma", use

\begin{proof}[Proof of lemma]

to omit the box, just before \end{proof} insert

\renewcommand{\qedsymbol}{}

(this does not persist after the proof ends.)

both features are described in the manual: texdoc amsthm