Okay, here's the deal. `GetPlayerState` returns:
1 - the player is participating
2 - the player won
3 - the player lost
4 - the player wasn't present initially.
The manual is full of mistakes.
Whether to use constants or not is up to you.
Regarding the unclear expression: everything is on the Lua language developer's website, lua.org, including operator precedence. I just used the available features, and ten extra parentheses won't make a difference.