Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review
Positive Existential Definability with Unit, Addition and Coprimeness. / Старчак, Михаил Романович.
ISSAC 2021 - Proceedings of the 2021 International Symposium on Symbolic and Algebraic Computation. Association for Computing Machinery, 2021. p. 353–360 (Proceedings of the International Symposium on Symbolic and Algebraic Computation, ISSAC).Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review
}
TY - GEN
T1 - Positive Existential Definability with Unit, Addition and Coprimeness
AU - Старчак, Михаил Романович
N1 - Conference code: 46
PY - 2021/7/18
Y1 - 2021/7/18
N2 - We consider positively existentially definable sets in the structure 〈ℤ; 1, +, ⊥〉 It is well known that the elementary theory of this structure is undecidable while the existential theory is decidable. We show that after the extension of the signature with the unary '-' functional symbol, binary symbols for dis-equality ≠ and GCD(·, ·) = d for every fixed positive integer d, every positive existential formula in this extended language is equivalent in ℤ to some positive quantifier-free formula. Then we get some corollaries from the main result. The binary order ≤ and dis-coprimeness ⊥ relations are not positively existentially definable in the structure 〈ℤ; 1, +, ⊥〉. Every positively existentially definable set in the structure 〈N; S, ⊥〉 is quantifier-free definable in 〈N; S, ≠, 0, ⊥〉. We also get a decidable fragment of the undecidable ∀∃-Theory of the structure 〈ℤ; 1, +, ≤, |〉, where | is a binary predicate symbol for the integer divisibility relation.
AB - We consider positively existentially definable sets in the structure 〈ℤ; 1, +, ⊥〉 It is well known that the elementary theory of this structure is undecidable while the existential theory is decidable. We show that after the extension of the signature with the unary '-' functional symbol, binary symbols for dis-equality ≠ and GCD(·, ·) = d for every fixed positive integer d, every positive existential formula in this extended language is equivalent in ℤ to some positive quantifier-free formula. Then we get some corollaries from the main result. The binary order ≤ and dis-coprimeness ⊥ relations are not positively existentially definable in the structure 〈ℤ; 1, +, ⊥〉. Every positively existentially definable set in the structure 〈N; S, ⊥〉 is quantifier-free definable in 〈N; S, ≠, 0, ⊥〉. We also get a decidable fragment of the undecidable ∀∃-Theory of the structure 〈ℤ; 1, +, ≤, |〉, where | is a binary predicate symbol for the integer divisibility relation.
KW - Existential definability
KW - Coprimeness
KW - Quantifier elimination
KW - Decidability
KW - Chinese remainder theorem
KW - chinese remainder theorem
KW - coprimeness
KW - decidability
KW - existential definability
KW - quantifier elimination
UR - http://www.scopus.com/inward/record.url?scp=85111087503&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/e0b4267d-fc48-3ec6-9639-5a5a3bb735a6/
U2 - 10.1145/3452143.3465515
DO - 10.1145/3452143.3465515
M3 - Conference contribution
T3 - Proceedings of the International Symposium on Symbolic and Algebraic Computation, ISSAC
SP - 353
EP - 360
BT - ISSAC 2021 - Proceedings of the 2021 International Symposium on Symbolic and Algebraic Computation
PB - Association for Computing Machinery
Y2 - 18 July 2021 through 23 July 2021
ER -
ID: 84459010