RGB stands for the red, green and blue layers of the semantic web layer cake
i.e. linked data (red), unifying logic (green) and pragmatic proof (blue).
RGB is a kind of mixed computation where both input and output can be
a mixture of data, logic and proof.
o Proof construction using the proof vocabulary
o Proof without @ keywords and without bindings
o Cwm Built-in functions
o Logic Framework Extension builtins
o RIF Datatypes and Built-Ins
o Prolog builtins
o Turtle without @ keywords
o Notation 3 graph literals