User blog comment:Tetramur/Well-defined Oblivion number (I think)/@comment-35470197-20200106221111/@comment-37993808-20200221064627

X is a complete system - that is, all formulas in X can be defined using pre-defined symbols (if you are using strings of symbols, then it counts as one symbol, for example, if you change the symbol "exists" into 2556 ones, then they all count as one symbol), and rules for them, as FOST, Fish system and FOOT do. So, if you count brackets as one symbol, then Rayo's system is K(6) and Fish oracle and FOOT are K(7). I can change the symbol "is equal to" to Graham's number of exclamation marks, and this is still one symbol.