Post Made Community Wiki by Harry Gindi
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Notation question:

What does $(\Delta^1)^{ \{1, \ldots,n-1 \}}$ denote? Note here: The 1,...,n-1 should be enclosed in curly braces, but it appears to be a limitation of the jsmath application to get those to work like they do in LaTeX. UPDATE: I (David Speyer) tried to fix the LaTeX. Please see if I got it right.

Vocabulary question:

Suppose $z:\Delta^{n+1} \rightarrow S$ is a morphism of simplicial sets. What does the following translate to in algebraic terms: $z|\Delta^{ \{0,\ldots,n \} }$ is a constant simplex at a vertex $x$. Note again the curly brace issue.

So mainly, I just don't know what that is supposed to mean, "is a constant simplex at the vertex x". Everything else makes fine sense.

I've searched through a number of books on homotopy theory, algebraic topology, etc. and I've been unable to find these precise usages.

I ask these questions only because I'm reading HTT by Lurie, and these usages come up and they're quite confusing.

2 added 119 characters in body

Notation question:

What does $(\Delta^1)^{1,...,n-1}$ (\Delta^1)^{ \{1, \ldots,n-1 \}}$denote? Note here: The 1,...,n-1 should be enclosed in curly braces, but it appears to be a limitation of the jsmath application to get those to work like they do in LaTeX. UPDATE: I (David Speyer) tried to fix the LaTeX. Please see if I got it right. Vocabulary question: Suppose$z:\Delta^{n+1} \rightarrow S$is a morphism of simplicial sets. What does the following translate to in algebraic terms:$z|\Delta^{0,...,n}$z|\Delta^{ \{0,\ldots,n \} }$ is a constant simplex at a vertex $x$. Note again the curly brace issue.

So mainly, I just don't know what that is supposed to mean, "is a constant simplex at the vertex x". Everything else makes fine sense.

I've searched through a number of books on homotopy theory, algebraic topology, etc. and I've been unable to find these precise usages.

I ask these questions only because I'm reading HTT by Lurie, and these usages come up and they're quite confusing.

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