abbrev
definition
MusicalIntervalStep
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IndisputableMonolith.Foundation.UniversalForcing.MusicRealization on GitHub at line 19.
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16open ArithmeticFromLogic
17open Invariance.Universal
18
19abbrev MusicalIntervalStep := Nat
20
21def musicCost (a b : MusicalIntervalStep) : Nat :=
22 if a = b then 0 else 1
23
24@[simp] theorem musicCost_self (a : MusicalIntervalStep) : musicCost a a = 0 := by
25 simp [musicCost]
26
27theorem musicCost_symm (a b : MusicalIntervalStep) : musicCost a b = musicCost b a := by
28 by_cases h : a = b
29 · subst h; simp [musicCost]
30 · have h' : b ≠ a := by intro hb; exact h hb.symm
31 simp [musicCost, h, h']
32
33def musicInterpret (n : LogicNat) : MusicalIntervalStep :=
34 LogicNat.toNat n
35
36/-- Musical realization as interval-step comparison. -/
37def musicRealization : LogicRealization where
38 Carrier := MusicalIntervalStep
39 Cost := Nat
40 zeroCost := inferInstance
41 compare := musicCost
42 zero := 0
43 step := Nat.succ
44 Orbit := LogicNat
45 orbitZero := LogicNat.zero
46 orbitStep := LogicNat.succ
47 interpret := musicInterpret
48 interpret_zero := by rfl
49 interpret_step := by