Abbreviations
The object ■n□ demonstrates the use of "abbreviation", a way to simplify the denoting of objects, and consequently discussions about them, once they have been created "officially". Done correctly the definition would proceed as follows:
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- ■□ ≡ ■1□, ■■□ ≡ ■2□, ■■■□ ≡ ■3□, etc, where the notions of ≡ ("defined as") and "number" are presupposed to be understood intuitively in the metatheory.
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Kurt Godel 1931 virtually constructed the entire proof of his incompleteness theorems (actually he proved Theorem IV and sketched a proof of Theorem XI) by use of this tactic, proceeding from his axioms using substitution, concatenation and deduction of modus ponens to produce a collection of 45 "definitions" (derivations or theorems more accurately) from the axioms.
A more familiar tactic is perhaps the design of subroutines that are given names, e.g. in Excel the subroutine " =INT(A1)" that returns to the cell where it is typed (e.g. cell B1) the integer it finds in cell A1.
Read more about this topic: Object Theory