Quick Question on Lp Space and Notation

I have a homework problem discussing the heat equation, and I have two questions about notation that I could not figure out through google searching:

$L^1(ℝ)$ as in a function $g\in C^1(ℝ)\cap L^1(ℝ)$

$||u(\bullet ,t)||_{L^∞}$

The bullet in the second expression is actually a single dot at that height, but I could not find the latex symbol for it. I initially thought it was a limit as $x\rightarrow\infty$ but that is incorrect.

Dick