尽管 EV 模型是,理论上,更多为测量错误在存在的应用拨出,人们仍然是使倾向使用平常的回归模型的更多;由于统计推理的困难的传统的 LS 方法;计算。在 EV 模型学习 LS 估计的表演因此是有意义的。在这篇文章,我们获得在线性 EV 模...尽管 EV 模型是,理论上,更多为测量错误在存在的应用拨出,人们仍然是使倾向使用平常的回归模型的更多;由于统计推理的困难的传统的 LS 方法;计算。在 EV 模型学习 LS 估计的表演因此是有意义的。在这篇文章,我们获得在线性 EV 模型保证回归系数的估计的 asymptotic 规度的一般条件。结果与在平常的回归模型的相应结果在某些方面不同,是显著的。展开更多
We extend the constraint data model to allow complex objects and study the expressive power of various query languages over this sort of constraint databases.The tools we use come in the form of collapse results which...We extend the constraint data model to allow complex objects and study the expressive power of various query languages over this sort of constraint databases.The tools we use come in the form of collapse results which are well established in the context of first-order logic.We show that the natural-active collapse with a condition and the activegeneric collapse carry over to the second-order logic for structures with o-minimality property and any signature in the complex value relations.The expressiveness results for more powerful logics including monadic second-order logic,monadic second-order logic with fix-point operators,and fragments of second-order logic are investigated in the paper.We discuss the data complexity for second-order logics over constraint databases.The main results are that the complexity upper bounds for three theories,MSO+(LIN),MSO+(POLY),and Inflationary DATALOGact^cv(SC,M)without powerset operator are∪iΣi^NC1,NCH=∪iΣi^NC,and AC^0/poly,respectively.We also consider the problem of query closure property in the context of embedded finite models and constraint databases with complex objects and the issue of how to determine safe constraint queries.展开更多
文摘尽管 EV 模型是,理论上,更多为测量错误在存在的应用拨出,人们仍然是使倾向使用平常的回归模型的更多;由于统计推理的困难的传统的 LS 方法;计算。在 EV 模型学习 LS 估计的表演因此是有意义的。在这篇文章,我们获得在线性 EV 模型保证回归系数的估计的 asymptotic 规度的一般条件。结果与在平常的回归模型的相应结果在某些方面不同,是显著的。
文摘We extend the constraint data model to allow complex objects and study the expressive power of various query languages over this sort of constraint databases.The tools we use come in the form of collapse results which are well established in the context of first-order logic.We show that the natural-active collapse with a condition and the activegeneric collapse carry over to the second-order logic for structures with o-minimality property and any signature in the complex value relations.The expressiveness results for more powerful logics including monadic second-order logic,monadic second-order logic with fix-point operators,and fragments of second-order logic are investigated in the paper.We discuss the data complexity for second-order logics over constraint databases.The main results are that the complexity upper bounds for three theories,MSO+(LIN),MSO+(POLY),and Inflationary DATALOGact^cv(SC,M)without powerset operator are∪iΣi^NC1,NCH=∪iΣi^NC,and AC^0/poly,respectively.We also consider the problem of query closure property in the context of embedded finite models and constraint databases with complex objects and the issue of how to determine safe constraint queries.