基于爬坡约束条件下的多时段竞价模型

本文建立了基于爬坡约束的多时段竞价模型,并通过数据模拟计算,分析比较,从中得出一些有用的结论.这些结论对进一步改善现有的竞价模型可以起到启发指导的作用.     

线性逻辑和态极逻辑引论(Ⅱ)

本文是《线性逻辑和态极逻辑引论》一文的第二部分。文章致力于证明网(第1节)和态极逻辑(第2,3,4和5节)证明网部分尽管局限于其积线性逻辑框架,但仍不失其重要性。线性逻辑和态极逻辑均为Girard所创建,近期所发展起来的态极逻辑旨在于进一步揭示计算和逻辑的基本交互作用的本质。我们希望本文能对这一新的理论带来一些计算机科学方面的启示。     

Software Tools for Geometrical Problem Solving: Potentials and Pitfalls

Dynamic geometry software provides tools for students to construct and experiment with geometrical objects and relationships. On the basis of their experimentation, students make conjectures that can be tested with the tools available. In this paper, we explore the role of software tools in geometry problem solving and how these tools, in interaction with activities that embed the goals of teachers and students, mediate the problem solving process. Through analysis of successful student responses, we show how dynamic software tools can not only scaffold the solution process but also help students move from argumentation to logical deduction. However, by reference to the work of less successful students, we illustrate how software tools that cannot be programmed to fit the goals of the students may prevent them from expressing their (correct) mathematical ideas and thus impede their problem solution.This revised version was published online in September 2005 with corrections to the Cover Date.     

On minimal Sturmian partial words

Partial words, which are sequences that may have some undefined positions called holes, can be viewed as sequences over an extended alphabet A_?=A∪{?}, where ? stands for a hole and matches (or is compatible with) every letter in A. The subword complexity of a partial word w, denoted by p_w(n), is the number of distinct full words (those without holes) over the alphabet that are compatible with factors of length n of w. A function f:N→N is (k,h)-feasible if for each integer N≥1, there exists a k-ary partial word w with h holes such that p_w(n)=f(n) for all n such that 1≤n≤N. We show that when dealing with feasibility in the context of finite binary partial words, the only affine functions that need investigation are f(n)=n+1 and f(n)=2n. It turns out that both are (2,h)-feasible for all non-negative integers h. We classify all minimal partial words with h holes of order N with respect to f(n)=n+1, called Sturmian, computing their lengths as well as their numbers, except when h=0 in which case we describe an algorithm that generates all minimal Sturmian full words. We show that up to reversal and complement, any minimal Sturmian partial word with one hole is of the form aⁱ?a^jba^l, where i,j,l are integers satisfying some restrictions, that all minimal Sturmian partial words with two holes are one-periodic, and that up to complement, ?(a^N−1?)^h−1 is the only minimal Sturmian partial word with h≥3 holes. Finally, we give upper bounds on the lengths of minimal partial words with respect to f(n)=2n, showing them tight for h=0,1 or 2.     

Source program optimization with a generalized FOR statement

A generalized FOR statement which includes multiple control variables was found to be a very powerful tool at the source program level for writing efficient FOR loops. This design of a generalized FOR statement grew out of a requirement to design a language that could be translated into efficient code with (almost) no optimizations done by its compiler.     

Dynamic microprogramming and external subroutine calls in a multics-type environment

A scheme is presented for external subroutine calls which makes it possible to have microprogrammed subroutines and to allow subroutines written in different languages. The languages may be compiled to different Directly Executed Languages (DELs) with corresponding microprogrammed interpreters. The scheme makes it possible to intercept each external subroutine call so that such actions as parameter validation, microprogram simulation, and statistics collection can be done. The scheme is intended to be working in a Multics-type environment with late dynamic linking, virtual memory, and ring protection. The scheme is adapted to a model of microprogram development which is also presented.     

Accelerating Branch-and-Bound through a Modeling Language Construct for Relaxation-Specific Constraints

In the tradition of modeling languages for optimization, a single model is passed to a solver for solution. In this paper, we extend BARON’s modeling language in order to facilitate the communication of problem-specific relaxation information from the modeler to the branch-and-bound solver. This effectively results into two models being passed from the modeling language to the solver. Three important application areas are identified and computational experiments are presented. In all cases, nonlinear constraints are provided only to the relaxation constructor in order to strengthen the lower bounding step of the algorithm without complicating the local search process. In the first application area, nonlinear constraints from the reformulation–linearization technique (RLT) are added to strengthen a problem formulation. This approach is illustrated for the pooling problem and computational results show that it results in a scheme that makes global optimization nearly as fast as local optimization for pooling problems from the literature. In the second application area, we communicate with the relaxation constructor the first-order optimality conditions for unconstrained global optimization problems. Computational experiments with polynomial programs demonstrate that this approach leads to a significant reduction of the size of the branch-and-bound search tree. In the third application, problem-specific nonlinear optimality conditions for the satisfiability problem are used to strengthen the lower bounding step and are found to significantly expedite the branch-and-bound algorithm when applied to a nonlinear formulation of this problem.     

Finite State and Finite Stop Quantum Languages

We propose the concept of finite stop quantum automata (ftqa) based on Hilbert space and compare it with the finite state quantum automata (fsqa) proposed by Moore and Crutchfield (Theoretical Computer Science 237(1–2), 2000, 275–306). The languages accepted by fsqa form a proper subset of the languages accepted by ftqa. In addition, the fsqa form an infinite hierarchy of language inclusion with respect to the dimensionality of unitary matrices. We introduce complex-valued acceptance degrees and two types of finite stop quantum automata based on them: the invariant ftqa (icftq) and the variant ftqa (vcftq). The languages accepted by icftq form a proper subset of the languages accepted by vcftq. In addition, the icftq form an infinite hierarchy of language inclusion with respect to the dimensionality of unitary matrices. In this way, we establish two proper inclusion relations (fsqa) ⊂ (ftqa) and (icftq) ⊂ (vcftq), where the symbol means languages, and two infinite language hierarchies (fsqa) ⊂ (fsqa), (icftq) (icftq).     

Access mechanisms in block structured environments

Statistics from dynamic analysis of programs are used to compare the efficiency of different methods to access global variables. The method where static links are used for access is shown to be at least as efficient as the display method. The use of the linked list method also leads to a simpler runtime system and allows separately compiled modules to execute at any level in the resulting program. The results of the dynamic analysis are presented in a form which allows comparison of the access methods in language implementations on specific computers. Experience with using two different access methods in an implementation of Simula67 concludes the paper.