Definition 14.11.1. Let $U$ be a simplicial set. We say $x$ is an $n$-simplex of $U$ to signify that $x$ is an element of $U_ n$. We say that $y$ is the $j$the face of $x$ to signify that $d^ n_ jx = y$. We say that $z$ is the $j$th degeneracy of $x$ if $z = s^ n_ jx$. A simplex is called degenerate if it is the degeneracy of another simplex.
Post a comment
Your email address will not be published. Required fields are marked.
In your comment you can use Markdown and LaTeX style mathematics (enclose it like
$\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).
All contributions are licensed under the GNU Free Documentation License.