Index sets for some classes of structures
نویسندگان
چکیده
منابع مشابه
Index sets for classes
A class is an e ectively closed set of reals We study properties of these classes determined by cardinality measure and category as well as by the complexity of the members of a class P Given an e ective enumeration fPe e g of the classes the index set I for a certain property such as having positive measure is the set of indices e such that Pe has the property For example the index set of bina...
متن کاملIndex Sets of Computable Structures
The index set of a computable structure A is the set of indices for computable copies of A. We determine the complexity of the index sets of various mathematically interesting structures, including arbitrary finite structures, Q-vector spaces, Archimedean real closed ordered fields, reduced Abelian p-groups of length less than ω, and models of the original Ehrenfeucht theory. The index sets for...
متن کاملinvestigating the feasibility of a proposed model for geometric design of deployable arch structures
deployable scissor type structures are composed of the so-called scissor-like elements (sles), which are connected to each other at an intermediate point through a pivotal connection and allow them to be folded into a compact bundle for storage or transport. several sles are connected to each other in order to form units with regular polygonal plan views. the sides and radii of the polygons are...
Index Sets of some Computable Groups
1 Acknowledgements I would first like to thank my advisor Professor Karen Lange. She has quite literally taught me everything I know about computability. She has helped me develop as not only a math researcher, but also a writer and presenter. I would also like to thank NSF grant DMS-1100604 for funding summer research that was instrumental in helping me complete this thesis. I would also like ...
متن کاملIndex Sets and Presentations of Complexity Classes ( revised
This paper draws close connections between the ease of presenting a given complexity class C and the position of the index sets IC = f i : L(Mi) 2 C g and JC = f i : Mi is total ^ L(Mi) = 2 C g in the arithmetical hierarchy. For virtually all classes C studied in the literature, the lowest levels attainable are IC 2 P03 and JC 2 Q02; the rst holds i C is 02-presentable, and the second i C is re...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Annals of Pure and Applied Logic
سال: 2009
ISSN: 0168-0072
DOI: 10.1016/j.apal.2008.09.006