What (who) is C Sharp 2 0 - definition

THE SET OF GÖDEL NUMBERS OF TRUE FORMULAS ABOUT THE INDISCERNIBLES IN THE GÖDEL CONSTRUCTIBLE UNIVERSE 𝐿

0♯; Sharp (set theory); 0 sharp; Zero-sharp; 0-sharp; Zero Sharp; Silver indiscernible

Zero sharp

In the mathematical discipline of set theory, 0# (zero sharp, also 0#) is the set of true formulae about indiscernibles and order-indiscernibles in the Gödel constructible universe. It is often encoded as a subset of the integers (using Gödel numbering), or as a subset of the hereditarily finite sets, or as a real number.

https://en.wikipedia.org/wiki/Zero_sharp

C♯ (musical note)

MUSICAL NOTE

C♯ (music); C-sharp (musical note); Hisis; B double-sharp; C sharp (note); C sharp (musical note); C-sharp (note)

C (C-sharp) is a musical note lying a chromatic semitone above C and a diatonic semitone below D. C-sharp is thus enharmonic to D.

https://en.wikipedia.org/wiki/C♯_(musical_note)

2-2-2-0

LOCOMOTIVE WHEEL ARRANGEMENT

2-(2-2)-0

Under the Whyte notation for the classification of steam locomotives, 2-2-2-0 usually represents the wheel arrangement of two leading wheels on one axle, four powered but uncoupled driving wheels on two axles, and no trailing wheels, but can also be used to represent two sets of leading wheels (not in a bogie truck) two driving wheels, and no trailing wheels. Some authorities place brackets around the duplicated but uncoupled wheels, creating a notation 2-(2-2)-0, or (2-2)-2-0,Baxter, pp.

https://en.wikipedia.org/wiki/2-2-2-0

Wikipedia

Zero sharp

In the mathematical discipline of set theory, 0^# (zero sharp, also 0#) is the set of true formulae about indiscernibles and order-indiscernibles in the Gödel constructible universe. It is often encoded as a subset of the integers (using Gödel numbering), or as a subset of the hereditarily finite sets, or as a real number. Its existence is unprovable in ZFC, the standard form of axiomatic set theory, but follows from a suitable large cardinal axiom. It was first introduced as a set of formulae in Silver's 1966 thesis, later published as Silver (1971), where it was denoted by Σ, and rediscovered by Solovay (1967, p.52), who considered it as a subset of the natural numbers and introduced the notation O^# (with a capital letter O; this later changed to the numeral '0').

Roughly speaking, if 0^# exists then the universe V of sets is much larger than the universe L of constructible sets, while if it does not exist then the universe of all sets is closely approximated by the constructible sets.

https://en.wikipedia.org/wiki/Zero sharp