defining my own proof environment?

Question

How would I define a proof environment that is basically used with

\begin{proof}
some proof here
\end{proof}

and it would be equivalent to:

\paragraph{Proof:} some proof here
\hfill \box

?

Answer 1

With LaTeX syntax:

\newenvironment{proof}{\paragraph{Proof:}}{\hfill\null}

I assume here that you mean \hbox{} not \box in your code. The \null macro is short for \hbox{}. The \box is a TeX primitive and is more like \usebox.

Answer 2

\def\QEDmark{\square}
\def\proof{\paragraph{Proof:}}
\def\endproof{\hfill\QEDmark}