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| Mirrors > Home > ILE Home > Th. List > eqid | GIF version | ||
| Description: Law of identity
(reflexivity of class equality).  Theorem 6.4 of [Quine]
       p. 41.
 This law is thought to have originated with Aristotle (Metaphysics, Zeta, 17, 1041 a, 10-20). (Thanks to Stefan Allan and BJ for this information.) (Contributed by NM, 5-Aug-1993.) (Revised by BJ, 14-Oct-2017.)  | 
| Ref | Expression | 
|---|---|
| eqid | ⊢ 𝐴 = 𝐴 | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | biid 171 | . 2 ⊢ (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐴) | |
| 2 | 1 | eqriv 2193 | 1 ⊢ 𝐴 = 𝐴 | 
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