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Theorem butlast-in

⊦ ¬ char ∈ str ∧ str ≠ "" → ¬ char ∈ str.butlast

Type: A user defined theorem
Validity: The proof is valid.
Features: simp, localsimp,
Comment:
Used by: right-trim-app,
Used by units in proved state:
Proof exists?: Yes

View the proof

Infos about the proof

Proved?: Yes
Interactions: 1
Proof steps: 2
Used lemmas: char-in-01, char-in, butlast-def,
Used spec theorems:
- Used simplifier rules:
  - string2list/s2l-empty-01
  - list-last/charlist/bin-01