In this paper we prove that if) is regularly bi-interpretable with the ring R. As a consequence of this theorem, we show that the class of all Chevalley groups over local rings (with the listed restrictions) is elementary definable, i. e., if for an arbitrary group H we have H ≡ G π (Φ, R), than there exists a ring R ′ ≡ R such that H ∼ = G π (Φ, R ′ ).