Head Normal Form Bisimulation for Pairs and the \lambda\mu-Calculus

Author(s):  
S.B. Lassen
Keyword(s):  



1998 ◽  
Vol 8 (6) ◽  
pp. 637-669 ◽  
Author(s):  
PHILIPPE de GROOTE

We introduce a natural deduction-like formalisation of Parigot's λμ-calculus. From this, we derive an environment machine that allows any well-typed λμ-term to be reduced to its weak head normal form. The soundness and completeness of the machine is proved.



2015 ◽  
Vol 26 (7) ◽  
pp. 1304-1350 ◽  
Author(s):  
SYLVAIN SALVATI ◽  
IGOR WALUKIEWICZ

Simply typed λ-calculus with fixpoint combinators, λY-calculus, offers an interesting method for approximating program semantics. The Böhm tree of a λY-term represents the meaning of the program up to the meaning of built-in constants. It is much easier to reason about properties of such trees than properties of interpreted programs. Moreover, some interesting properties of programs are already expressible on the level of these trees.Collapsible pushdown automata (CPDA) give another way of generating the same class of trees as λY-terms. We clarify the relationship between the two models. In particular, we present two relatively simple translations from λY-terms to CPDA using Krivine machines as an intermediate step. The latter are general machines for describing computation of the weak head normal form in the λ-calculus. They provide the notions of closure and environment that facilitate reasoning about computation.



Author(s):  
A. V. Crewe

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.



2012 ◽  
Vol 132 (8) ◽  
pp. 698-699 ◽  
Author(s):  
Hideaki Wakabayashi ◽  
Jiro Yamakita


Author(s):  
N.I. Gdansky ◽  
◽  
A.A. Denisov ◽  

The article explores the satisfiability of conjunctive normal forms used in modeling systems.The problems of CNF preprocessing are considered.The analysis of particular methods for reducing this formulas, which have polynomial input complexity is given.



Author(s):  
David Julian Gonzalez Maldonado ◽  
Peter Hagedorn ◽  
Thiago Ritto ◽  
Rubens Sampaio ◽  
Artem Karev


Author(s):  
V. F. Edneral ◽  
O. D. Timofeevskaya

Introduction:The method of resonant normal form is based on reducing a system of nonlinear ordinary differential equations to a simpler form, easier to explore. Moreover, for a number of autonomous nonlinear problems, it is possible to obtain explicit formulas which approximate numerical calculations of families of their periodic solutions. Replacing numerical calculations with their precalculated formulas leads to significant savings in computational time. Similar calculations were made earlier, but their accuracy was insufficient, and their complexity was very high.Purpose:Application of the resonant normal form method and a software package developed for these purposes to fourth-order systems in order to increase the calculation speed.Results:It has been shown that with the help of a single algorithm it is possible to study equations of high orders (4th and higher). Comparing the tabulation of the obtained formulas with the numerical solutions of the corresponding equations shows good quantitative agreement. Moreover, the speed of calculation by prepared approximating formulas is orders of magnitude greater than the numerical calculation speed. The obtained approximations can also be successfully applied to unstable solutions. For example, in the Henon — Heyles system, periodic solutions are surrounded by chaotic solutions and, when numerically integrated, the algorithms are often unstable on them.Practical relevance:The developed approach can be used in the simulation of physical and biological systems.



2015 ◽  
Author(s):  
Gabriel Frahm


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