Refinement Type Inference via Horn Constraint Optimization

We propose a novel method for inferring refinement types of higher-order functional programs. The main advantage of the proposed method is that it can infer maximally preferred (i.e., Pareto optimal) refinement types with respect to a user-specified preference order. The flexible optimization of refinement types enabled by the proposed method paves the way for interesting applications, such as inferring most-general characterization of inputs for which a given program satisfies (or violates) a given safety (or termination) property. Our method reduces such a type optimization problem to a Horn constraint optimization problem by using a new refinement type system that can flexibly reason about non-determinism in programs. Our method then solves the constraint optimization problem by repeatedly improving a current solution until convergence via template-based invariant generation. We have implemented a prototype inference system based on our method, and obtained promising results in preliminary experiments.Comment: 19 page

Sharper and Simpler Nonlinear Interpolants for Program Verification

Interpolation of jointly infeasible predicates plays important roles in various program verification techniques such as invariant synthesis and CEGAR. Intrigued by the recent result by Dai et al.\ that combines real algebraic geometry and SDP optimization in synthesis of polynomial interpolants, the current paper contributes its enhancement that yields sharper and simpler interpolants. The enhancement is made possible by: theoretical observations in real algebraic geometry; and our continued fraction-based algorithm that rounds off (potentially erroneous) numerical solutions of SDP solvers. Experiment results support our tool's effectiveness; we also demonstrate the benefit of sharp and simple interpolants in program verification examples

A simple abstraction of arrays and maps by program translation

We present an approach for the static analysis of programs handling arrays, with a Galois connection between the semantics of the array program and semantics of purely scalar operations. The simplest way to implement it is by automatic, syntactic transformation of the array program into a scalar program followed analysis of the scalar program with any static analysis technique (abstract interpretation, acceleration, predicate abstraction,.. .). The scalars invariants thus obtained are translated back onto the original program as universally quantified array invariants. We illustrate our approach on a variety of examples, leading to the " Dutch flag " algorithm

Software Model Checking with Explicit Scheduler and Symbolic Threads

In many practical application domains, the software is organized into a set of threads, whose activation is exclusive and controlled by a cooperative scheduling policy: threads execute, without any interruption, until they either terminate or yield the control explicitly to the scheduler. The formal verification of such software poses significant challenges. On the one side, each thread may have infinite state space, and might call for abstraction. On the other side, the scheduling policy is often important for correctness, and an approach based on abstracting the scheduler may result in loss of precision and false positives. Unfortunately, the translation of the problem into a purely sequential software model checking problem turns out to be highly inefficient for the available technologies. We propose a software model checking technique that exploits the intrinsic structure of these programs. Each thread is translated into a separate sequential program and explored symbolically with lazy abstraction, while the overall verification is orchestrated by the direct execution of the scheduler. The approach is optimized by filtering the exploration of the scheduler with the integration of partial-order reduction. The technique, called ESST (Explicit Scheduler, Symbolic Threads) has been implemented and experimentally evaluated on a significant set of benchmarks. The results demonstrate that ESST technique is way more effective than software model checking applied to the sequentialized programs, and that partial-order reduction can lead to further performance improvements.Comment: 40 pages, 10 figures, accepted for publication in journal of logical methods in computer scienc

A Postulate for Tiger Recovery: The Case of the Caspian Tiger

Recent genetic analysis has shown that the extinct Caspian Tiger (P. t. virgata) and the living Amur Tigers (P. t. altaica) of the Russian Far East are actually taxonomically synonymous and that Caspian and Amur groups historically formed a single population, only becoming separated within the last 200 years by human agency. A major conservation implication of this finding is that tigers of Amur stock might be reintroduced, not only back into the Koreas and China as is now proposed, but also through vast areas of Central Asia where the Caspian tiger once lived. However, under the current tiger conservation framework the 12 “Caspian Tiger States” are not fully involved in conservation planning. Equal recognition as “Tiger Range States” should be given to the countries where the Caspian tiger once lived and their involvement in tiger conservation planning encouraged. Today, preliminary ecological surveys show that some sparsely populated areas of Central Asia preserve natural habitat suitable for tigers. In depth assessments should be completed in these and other areas of the Caspian range to evaluate the possibility of tiger reintroductions. Because tigers are a charismatic umbrella species, both ecologically and politically, reintroduction to these landscapes would provide an effective conservation framework for the protection of many species in addition to tigers. And for today’s Amur Tigers this added range will provide a buffer against further loss of genetic diversity, one which will maintain that diversity in the face of selective pressures that can only be experienced in the wild

ENDOPHYTIC BACTERIA AS BIOFERTILIZERS FOR MAIZE (ZEA MAYS L.)

Total ten isolates of endophytic bacteria mainly belonging to genera Acetobacter and Azospirillum having higher nitrogen fixing efficiency were isolated from surface sterilized plant parts of different plant species using LGIP and NFB media selective for growth of Acetobacter and Azospirillum respectively. All the isolates can colonize maize endophytically under laboratory conditions. In vitro nitrogen fixation rates of all the isolates ranged from 4.0 to 36.3 mg N fixed / gm of sugar consumed among which isolate A 10 showed the highest N fixing capacity i.e. 36.3 mg /g of sugar. All the isolates were also capable of solubilizing tri calcium phosphate in Pikovskaya’s broth, the soluble phosphate content was found in the range of 1.19 - 21.0 μg/ml and 4.44-23.81 μg/ml at 3 and 5 DAI, respectively. Seed inoculation of all the isolates significantly influenced growth of maize cv. Narmada moti in lab and field conditions. The highest grain yield (5694 Kg/ha) was obtained when seeds were inoculated with isolate A 10 was applied alongwith 75% recommended dose (RD) of N fertilizer which was significantly superior as compared to 100 % RD of chemical N fertilizer sowing savings of 25% of Nitrogenous fertilizer through bacterization

Pancreatic Head Mass from Metastatic Meningeal Hemangiopericytoma

Purpose. To illustrate the propensity of meningeal hemangiopericytoma to spread extraneurally, as a distinction to the ordinary meningioma

Tigers of Sundarbans in India: Is the Population a Separate Conservation Unit?

The Sundarbans tiger inhabits a unique mangrove habitat and are morphologically distinct from the recognized tiger subspecies in terms of skull morphometrics and body size. Thus, there is an urgent need to assess their ecological and genetic distinctiveness and determine if Sundarbans tigers should be defined and managed as separate conservation unit. We utilized nine microsatellites and 3 kb from four mitochondrial DNA (mtDNA) genes to estimate genetic variability, population structure, demographic parameters and visualize historic and contemporary connectivity among tiger populations from Sundarbans and mainland India. We also evaluated the traits that determine exchangeability or adaptive differences among tiger populations. Data from both markers suggest that Sundarbans tiger is not a separate tiger subspecies and should be regarded as Bengal tiger (P. t. tigris) subspecies. Maximum likelihood phylogenetic analyses of the mtDNA data revealed reciprocal monophyly. Genetic differentiation was found stronger for mtDNA than nuclear DNA. Microsatellite markers indicated low genetic variation in Sundarbans tigers (He= 0.58) as compared to other mainland populations, such as northern and Peninsular (Hebetween 0.67- 0.70). Molecular data supports migration between mainland and Sundarbans populations until very recent times. We attribute this reduction in gene flow to accelerated fragmentation and habitat alteration in the landscape over the past few centuries. Demographic analyses suggest that Sundarbans tigers have diverged recently from peninsular tiger population within last 2000 years. Sundarbans tigers are the most divergent group of Bengal tigers, and ecologically non-exchangeable with other tiger populations, and thus should be managed as a separate "evolutionarily significant unit" (ESU) following the adaptive evolutionary conservation (AEC) concept.Wildlife Institute of India, Dehra Dun (India)

Karakterizacija gena ICP4 patogenoga virusa Marekove bolesti dokazanoga u peradi u Gujaratu u Indiji lančanom reakcijom polimerazom i sekvenciranjem

A total of 34 clinical samples were collected for detection of Marek’s disease virus (MDV) by polymerase chain reaction assays using primers M1.1/M1.8 to amplify a region of the ICP4 gene in layer birds of poultry. Primer set M1.1/M1.8 amplified a 318 bp product as against the expected 247 bp product in 30 samples out of 34 samples tested. To confirm the result, this primer was subjected to NCBI BLAST, and it was found that the primer specific segment of 318 bp does exist in the published sequence of Md5 and Md11BAC. The PCR product was sequenced and resulted in 273bp by direct sequencing. The sequence was analysed using NCBI blast and Clustal W with the published sequence of Gallid herpes virus-2 giving a matching score of 97, 96 and 90% indicating a highly conserved region. This shows that the MDV is prevalent in Gujarat.Prikupljena su 34 uzorka kliničkoga materijala nesilica za dokaz virusa Marekove bolesti lančanom reakcijom polimerazom uporabom početnica M1.1/M1.8 za umnažanje područja gena ICP4. Uporabom seta početnica M1.1/M1.8 umnožen je proizvod od 318 bp u odnosu na očekivani od 247 bp u 30 od 34 pretražena uzorka. Za potvrdu rezultata početnica je bila analizirana pomoću programa NCBI BLAST, te je ustanovljeno da početnica za specifičan odsječak od 318 bp postoji u objavljenoj sekvenci Md5 i Md11BAC. Proizvod PCR-a bio je izravno sekvenciran te je ustanovljeno da sadrži 273 bp. Slijed je bio analiziran uporabom programa NCBI BLAST i Clustal W i uspoređen s objavljenim slijedom za kokošji herpesvirus 2 te je ustanovljena podudarnost od 97, 96 i 90% što upućuje na genski jako očuvano područje. To pokazuje da je virus Marekove bolesti proširen u Gujaratu