LaTeX tip #4

Tip below requires the amslatex macros.
These are automatically loaded if you use the amsart documentclass, but if you use other documentclasses, such as article, put the following in the preamble, after \documentclass{...}: \usepackage{amsmath, amsthm, amssymb} .

Theorem and Proof enviroment can be done in LaTeX as follows:

\newtheorem{Task}{Task}
\newcommand{\change}{}
\newenvironment{Exc}{\begin{Task} \rm}{\hfill $\Box$ \end{Task}}

More on the same topic: LaTeX tips: Theorems