How to read and interpret the following mathematical notation? $\Gamma_{su} = \frac{P_sG_{su}}{\sum_{i\in S\{\backslash s\}}P_iG_{iu}+P_{AWGN}}$

Question

I came across the following expression in a research paper:

$$\Gamma_{su} = \frac{P_sG_{su}}{\sum_{i\in S\{\backslash s\}}P_iG_{iu}+P_{AWGN}}$$

My query is how to read that small $s$ in denominator which has left slash with it.

Any help in this regard will be highly appreciated.

Answer 1

The Equation 2 in the research paper is

$$\Gamma_{su} = \frac{P_sG_{su}}{\sum_{i\in S\backslash\{ s\}}P_iG_{iu}+P_{AWGN}}$$

The notation $S\backslash\{ s\}$ usually means set difference which is $S - \{s\}$ in this case where $\{s\}$ is the set containing a single element $s$. Hence, the denominator of the expression has the sum of $P_iG_{iu}$ for all $i \in S$ apart from $s$.