Notation
If you are new to logic, you can skip this. It is an explanation of the notation we are going to use and why.
The various logical systems can use Rabc or R(a,b,c) to symbolize the application of the predicate R to the arguments a, b, c. Often, when working informally, authors and Users would like to write Red(x) to mean that the predicate Red is applied to the variable x. We can do this within the formal system only if we choose the R(a,b,c) style of notation (because you have to be able to tell when the predicate stops and when the arguments start).