72,172 research outputs found

    Vol. 2 (pp. 677-1996). “Library notes” by researcher: summaries and long excerpts of testimony by workers about Margaret Schwartz’s death in the fire; engineers, laborers, and hardware dealer about condition of door casing, handrail, lock; and co-defendant/owner Max Blanck about his actions on day of fire

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    Vol. 2 (pp. 677-1996) “Library Notes,” picks up at page 677, continues to p. 1996 (61-page document), includes excerpts from transcript, more testimony from workers about the fire, what happened to Margaret Schwartz; testimony by engineer as to condition of door casing, handrail, staircases; testimony by engineer and hardware dealer about lock, laborers who found the lock; testimony of owner Max Blanck as to his actions on day of fir

    On algorithmic equivalence of instruction sequences for computing bit string functions

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    Every partial function from bit strings of a given length to bit strings of a possibly different given length can be computed by a finite instruction sequence that contains only instructions to set and get the content of Boolean registers, forward jump instructions, and a termination instruction. We look for an equivalence relation on instruction sequences of this kind that captures to a reasonable degree the intuitive notion that two instruction sequences express the same algorithm.Comment: 27 pages, the preliminaries have textual overlaps with the preliminaries in arXiv:1308.0219 [cs.PL], arXiv:1312.1529 [cs.PL], and arXiv:1312.1812 [cs.PL]; 27 pages, three paragraphs about Milner's algorithmic equivalence hypothesis added to concluding remarks; 26 pages, several minor improvements of the presentation mad

    Instruction sequence processing operators

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    Instruction sequence is a key concept in practice, but it has as yet not come prominently into the picture in theoretical circles. This paper concerns instruction sequences, the behaviours produced by them under execution, the interaction between these behaviours and components of the execution environment, and two issues relating to computability theory. Positioning Turing's result regarding the undecidability of the halting problem as a result about programs rather than machines, and taking instruction sequences as programs, we analyse the autosolvability requirement that a program of a certain kind must solve the halting problem for all programs of that kind. We present novel results concerning this autosolvability requirement. The analysis is streamlined by using the notion of a functional unit, which is an abstract state-based model of a machine. In the case where the behaviours exhibited by a component of an execution environment can be viewed as the behaviours of a machine in its different states, the behaviours concerned are completely determined by a functional unit. The above-mentioned analysis involves functional units whose possible states represent the possible contents of the tapes of Turing machines with a particular tape alphabet. We also investigate functional units whose possible states are the natural numbers. This investigation yields a novel computability result, viz. the existence of a universal computable functional unit for natural numbers.Comment: 37 pages; missing equations in table 3 added; combined with arXiv:0911.1851 [cs.PL] and arXiv:0911.5018 [cs.LO]; introduction and concluding remarks rewritten; remarks and examples added; minor error in proof of theorem 4 correcte

    Functional units for natural numbers

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    Interaction with services provided by an execution environment forms part of the behaviours exhibited by instruction sequences under execution. Mechanisms related to the kind of interaction in question have been proposed in the setting of thread algebra. Like thread, service is an abstract behavioural concept. The concept of a functional unit is similar to the concept of a service, but more concrete. A state space is inherent in the concept of a functional unit, whereas it is not inherent in the concept of a service. In this paper, we establish the existence of a universal computable functional unit for natural numbers and related results.Comment: 17 pages; notational mistakes in tables 5 and 6 corrected; erroneous definition at bottom of page 9 correcte

    Healthy Schools Program Evaluation: Year 1 Update

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    Assesses the early impact of RWJF's program to provide technical assistance, resource brokering, and online tools to help schools promote physical activity and meet healthy foods and beverages standards. Examines improvement levels by school traits

    Programming an interpreter using molecular dynamics

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    PGA (ProGram Algebra) is an algebra of programs which concerns programs in their simplest form: sequences of instructions. Molecular dynamics is a simple model of computation developed in the setting of PGA, which bears on the use of dynamic data structures in programming. We consider the programming of an interpreter for a program notation that is close to existing assembly languages using PGA with the primitives of molecular dynamics as basic instructions. It happens that, although primarily meant for explaining programming language features relating to the use of dynamic data structures, the collection of primitives of molecular dynamics in itself is suited to our programming wants.Comment: 27 page

    Optimizing the SICStus Prolog virtual machine instruction set

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    The Swedish Institute of Computer Science (SICS) is the vendor of SICStus Prolog. To decrease execution time and reduce space requirements, variants of SICStus Prolog's virtual instruction set were investigated. Semi-automatic ways of finding candidate sets of instructions to combine or specialize were developed and used. Several virtual machines were implemented and the relationship between improvements by combinations and by specializations were investigated. The benefits of specializations and combinations of instructions to the performance of the emulator is on the average of the order of 10%. The code size reduction is 15%
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