Um colorido {\it tour} pelo $R^{\,4}$}

Resumo

The real vector 4--space is visited using some tools, new or little known by physicists, such as the symbol\, $\infty^n$\, and a 3--dimensional model for the subspaces. A direction is priviledged, allowing a color code for the vectors and easy perception of subspaces with 2 and 3 dimensions. Detailed tables of inclusions and normalities among all subspaces are displayed.