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Theorem indef

⊦ a ∈ s ↔ (∃ s0. s = s0 ++ a ∧ ¬ a ∈ s0)

Type: A user defined theorem
Validity: The proof is valid.
Features:
Comment:
Used by: size-exgr, size-one, size-three-01, size-three-02, size-two, sizesubl, subsize-eq,
Used by units in proved state: set-union,
Proof exists?: Yes

View the proof

Infos about the proof

Proved?: Yes
Interactions: 1
Proof steps: 4
Used lemmas: del, ne-02, ne-01, in-03,
Used spec theorems:
- Used simplifier rules: