Results 1 
3 of
3
The complexity of datalog on linear orders
, 2009
"... We study the program complexity of datalog on both finite and infinite linear orders. Our main result states that on all linear orders with at least two elements, the nonemptiness problem for datalog is EXPTIMEcomplete. While containment of the nonemptiness problem in EXPTIME is known for finite ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
We study the program complexity of datalog on both finite and infinite linear orders. Our main result states that on all linear orders with at least two elements, the nonemptiness problem for datalog is EXPTIMEcomplete. While containment of the nonemptiness problem in EXPTIME is known for finite linear orders and actually for arbitrary finite structures, it is not obvious for infinite linear orders. It sharply contrasts the situation on other infinite structures; for example, the datalog nonemptiness problem on an infinite successor structure is undecidable. We extend our upper bound results to infinite linear orders with constants. As an application, we show that the datalog nonemptiness problem on Allen’s interval algebra is EXPTIMEcomplete.
Linearizing bad sequences: upper bounds for the product and majoring well quasiorders
"... Abstract. Well quasiorders (wqo’s) are an important mathematical tool for proving termination of many algorithms. Under some assumptions upper bounds for the computational complexity of such algorithms can be extracted by analyzing the length of controlled bad sequences. We develop a new, selfcont ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
Abstract. Well quasiorders (wqo’s) are an important mathematical tool for proving termination of many algorithms. Under some assumptions upper bounds for the computational complexity of such algorithms can be extracted by analyzing the length of controlled bad sequences. We develop a new, selfcontained study of the length of bad sequences over the product ordering of N n, which leads to known results but with a much simpler argument. We also give a new tight upper bound for the length of the longest controlled descending sequence of multisets of N n, and use it to give an upper bound for the length of controlled bad sequences in the majoring ordering of sets of tuples. We apply this upper bound to obtain complexity upper bounds for decision procedures of automata over data trees. In both cases the idea is to linearize bad sequences, i.e. transform them into a descending one over a wellorder for which upper bounds can be more easily handled. 1
Universidad de Buenos Aires Facultad
"... Técnicas de razonamiento automático para lógicas híbridas Tesis presentada para optar al título de Doctor de la Universidad de Buenos Aires en el área de Ciencias de la Computación. ..."
Abstract
 Add to MetaCart
(Show Context)
Técnicas de razonamiento automático para lógicas híbridas Tesis presentada para optar al título de Doctor de la Universidad de Buenos Aires en el área de Ciencias de la Computación.