# Construct polynomial ring from list of variables

In constructing polynomial rings, documentation says that diamond brackets are used "to make the variable ready for use after you define the ring", but the variables are entered explicitly: `R.<x,y>`

.

What if I have a list of (an unknown number of) variables?

E.g. if I have xs = [x_1,x_2,x_3], I want to construct a polynomial ring and subsequently manipulate x_1 + x_2, etc., within that ring instead of "symbolic ring". I'd like to do something like `R.<xs>`

but that doesn't seem to work.