Checking Properties Described by State Machines: On Synergy of Instrumentation, Slicing, and Symbolic Execution

We introduce a novel technique for checking properties described by finite state machines. The technique is based on a synergy of three well-known methods: instrumentation, program slicing, and symbolic execution. More precisely, we instrument a given program with a code that tracks runs of state machines representing various properties. Next we slice the program to reduce its size without affecting runs of state machines. And then we symbolically execute the sliced program to find real violations of the checked properties, i.e. real bugs. Depending on the kind of symbolic execution, the technique can be applied as a stand-alone bug finding technique, or to weed out some false positives from an output of another bug-finding tool. We provide several examples demonstrating the practical applicability of our technique.Představujeme novou techniku pro ověřování vlastností popsaných konečně-stavovými stroji. Tato technika je založena na synergii tří známých metod: instrumentace, prořezání programu a symbolické vykonání. Přesněji, instrumentujeme daný program kódem, který sleduje běh stavových strojů představujících různé vlastnosti. Dále program prořežeme, abychom zmenšili jeho velikost při zachování běhů stavových strojů. Nakonec prořezaný program symbolicky vykonáme, abychom našli skutečné porušení ověřovaných vlastností, t.j. skutečné chyby. Podle použitého druhu symbolického vykonání může být tato technika použita jako samostatná metoda pro detekci chyb nebo k vytřídění některých falešných hlášení z výstupu jiných nástrojů pro detekci chyb. Poskytujeme několik příkladů, které dokumentují praktickou použitelnost naší techniky

Collaborative Verification and Testing with Explicit Assumptions

Many mainstream static code checkers make a number of compromises to improve automation, performance, and accuracy. These compromises include not checking certain program properties as well as making implicit, unsound assumptions. Consequently, the results of such static checkers do not provide definite guarantees about program correctness, which makes it unclear which properties remain to be tested. We propose a technique for collaborative verification and testing that makes compromises of static checkers explicit such that they can be compensated for by complementary checkers or testing. Our experiments suggest that our technique finds more errors and proves more properties than static checking alone, testing alone, and combinations that do not explicitly document the compromises made by static checkers. Our technique is also useful to obtain small test suites for partially-verified programs

Two-magnon Raman scattering in insulating cuprates: Modifications of the effective Raman operator

Calculations of Raman scattering intensities in spin 1/2 square-lattice Heisenberg model, using the Fleury-Loudon-Elliott theory, have so far been unable to describe the broad line shape and asymmetry of the two magnon peak found experimentally in the cuprate materials. Even more notably, the polarization selection rules are violated with respect to the Fleury-Loudon-Elliott theory. There is comparable scattering in $B_{1g}$ and $A_{1g}$ geometries, whereas the theory would predict scattering in only $B_{1g}$ geometry. We review various suggestions for this discrepency and suggest that at least part of the problem can be addressed by modifying the effective Raman Hamiltonian, allowing for two-magnon states with arbitrary total momentum. Such an approach based on the Sawatzsky-Lorenzana theory of optical absorption assumes an important role of phonons as momentum sinks. It leaves the low energy physics of the Heisenberg model unchanged but substantially alters the Raman line-shape and selection rules, bringing the results closer to experiments.Comment: 7 pages, 6 figures, revtex. Contains some minor revisions from previous versio

Spin Excitations in La2CuO4: Consistent Description by Inclusion of Ring-Exchange

We consider the square lattice Heisenberg antiferromagnet with plaquette ring exchange and a finite interlayer coupling leading to a consistent description of the spin-wave excitation spectrum in La2CuO4. The values of the in-plane exchange parameters, including ring-exchange J_{\Box}, are obtained consistently by an accurate fit to the experimentally observed in-plane spin-wave dispersion, while the out-of-plane exchange interaction is found from the temperature dependence of the sublattice magnetization at low temperatures. The fitted exchange interactions J=151.9 meV and J_{\Box}=0.24 J give values for the spin stiffness and the Neel temperature in excellent agreement with the experimental data.Comment: 4 pages, 1 figure, RevTe

Feasibility study on Intensive polyculture of chainess and Indian carps in I.R.IRAN (Giulan province)

500000 juvenile Indian majour carps (Labeo rohita,Cirhinus merigala, Catla catla) imported (2004) and transferred to the earthen ponds in Shahid Ansari Carp Breeding Center , In order to assess the viability of rearing under the climatic condition of north part of Iran and also achieve some growth parameters from the larval stage to market size.The fry with 300 mg weight, were released in to 8 ponds.specimens were separated to tree experimental categories: 1= (Labeo rohita) , 2= (Cirhinus merigala) , 3= (Catla catla). fishes were fed with artificial food and also with the natural products of the ponds which were enriched with organic fertilizers, after being equally stocked in the ponds .During the experiment, oxygen level ,PH, turbidity, and temperature were measured . Monthly fry samples were taken, for weight and length biometrical analysis and also determination of the weight gain percentage, average daily growth rate, specific growth rate. Results have indicated adaptations and considerable growth in this species, with an increase from the initial weight of 300 mg to an average of 13.5±1.6 mg in 50 days period until the end of November for fingerlings. Also the average weight of growing phase (second year of production) was 647g. For Labeo rohita ,420 g. for Cirhinus merigala and 734g. For Catla catla. The special growth rate(SGR)in Roho was 4.51 %.and 3.9 % for merigal and6.2 % for Catla while for Chinees carps SGR was 4.9, 6.7, 7.6 and 5.8 for silver carp,grass carp, common carp and big head respectively. Results revealed that the Indian majour carps compatibility with the condition in Gilan province was succesfull and the combination of species and optimization of their compatibility were remind for further studies

TRACER: A symbolic execution tool for verification

10.1007/978-3-642-31424-7_61Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)7358 LNCS758-76