On pg. 54 of a Quantum Computing textbook (Nielsen and Chuang), it's said that:
it is not surprising that similar techniques can be used to compress the source so that only $H(p, 1 − p)$ qubits are required to store the compressed source, where $H(·)$ is again the Shannon entropy function.
I'm confused with the use of the symbol "·" and I wonder what's the name of it as how it's used.