Undecidability of local structures of s-degrees and Q-degrees
نویسندگان
چکیده
We show that the first order theory of the Σ2 s-degrees is undecidable. Via isomorphism of the s-degrees with the Q-degrees, this also shows that the first order theory of the Π2 Q-degrees is undecidable. Together with a result of Nies, the proof of the undecidability of the Σ2 s-degrees yields a new proof of the known fact (due to Downey, LaForte and Nies) that the first order theory of the c.e. Q-degrees is undecidable.
منابع مشابه
Design and fabrication of a high-Q near-field probe for subsurface crack detection
Non-destructive detection and evaluation of invisible cracks in metal structures is an important matter in several critical environments including ground transportation, air transportation and power plants. In this paper, a high-Q near-field Microwave probe is designed and fabricated using defected ground structures for surface and subsurface crack detection in metal structures. For this purpos...
متن کاملDamage detection of structures using modal strain energy with Guyan reduction method
The subject of structural health monitoring and damage identification of structures at the earliest possible stage has been a noteworthy topic for researchers in the last years. Modal strain energy (MSE) based index is one of the efficient methods which are commonly used for detecting damage in structures. It is also more effective and economical to employ some methods for reducing the degrees ...
متن کاملFinite groups with three relative commutativity degrees
For a finite group $G$ and a subgroup $H$ of $G$, the relative commutativity degree of $H$ in $G$, denoted by $d(H,G)$, is the probability that an element of $H$ commutes with an element of $G$. Let $mathcal{D}(G)={d(H,G):Hleq G}$ be the set of all relative commutativity degrees of subgroups of $G$. It is shown that a finite group $G$ admits three relative commutativity degrees if a...
متن کاملDegrees of M-fuzzy families of independent L-fuzzy sets
The present paper studies fuzzy matroids in view of degree. First wegeneralize the notion of $(L,M)$-fuzzy independent structure byintroducing the degree of $M$-fuzzy family of independent $L$-fuzzysets with respect to a mapping from $L^X$ to $M$. Such kind ofdegrees is proved to satisfy some axioms similar to those satisfiedby $(L,M)$-fuzzy independent structure. ...
متن کاملLocal Imperfection Effects on Thermal Buckling Behavior of Composite Fiber Reinforced Truncated Conical Liner
Thermal buckling behavior of truncated conical liner reinforced by laminated composite is investigated in the presence of a general initial imperfection. For this purpose, the method of virtual work and first-order strain-deformation shell theory are employed to extract equilibrium equations. To this end, a finite element code is developed using the 3D 8-node shell element with six degrees of f...
متن کامل