I am trying use the package `listofsymbols` to define a symbol to be included in a list of symbols in a book. I have problems using the command `\newsym` to define a symbol which involves the command `\cdots`.

The following is a simple symbol definition that illustrates the problem:

```
\opensymdef
\newsym[A family of sets]{sFam}{A_{1},\cdots,A_{n}}
\closesymdef

```

When a document which includes the symbols file is compiled, `pdflatex` issues the the following error messages:

```
Undefined control sequence.
Undefined control sequence.
Undefined control sequence.
Undefined control sequence.
Undefined control sequence.

```

The description of the error is:

```
... family of sets]{sFam}{A_{1},\cdots,A_{n}}

The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

```

If `\cdots` is replaced with a string such as `xxxx` or a command such as `\alpha`, in the above symbol definition, then `pdflatex` compiles the document.

Could someone help me sort out this problem. Any help would be appreciated highly.