bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effective Insecticidal Activity of the two Extracts Ethyl Acetate and Hexan of Trichilia gilgiana against Sitophilus zeamaïs
Authors: Lucie Aba-Toumnou , Solange Patricia Wango , Ephrem Kosh-Komba , Salomon Namkosséréna , Serge Florent Bolevane-Ouatinam , Ponel-Béranger Lakouèténé Didier , Silla SEMBALLA , Olga-Diane YONGO , Jean-Laurent SYSSA-MAGALE , SECK Dogo , Mbacké Sembène
Published: February 2016

Post-harvest losses are recognized to be one of the critical constraints upon food security among farmers of poor resource in Africa.The use of botanical pesticides in pest management during storage against insects is often encouraged because synthetic insecticides produce multiple side-effects on human health and environment. Insecticidal activity of the hexane, dichloromethane, ethyl acetate and methanol extracts of bark of Trichilia gilgiana was tested on Sitophilus zeamaïs, Tribolium castaneum and Rhyzopertha dominica. The mortality rate was measured variable. The results of analysis showed that the mortality rate has a very highly significant variation following extracts, doses, insects and time considered (P < 0.001). Extracts with ethyl acetate and hexane of Trichilia gilgiana are effective against S. zeamais at the highest doses (1 g/ 10 mL and 0.5 g/10 mL of solvent). These effective extracts were characterized by gas chromatography coupled with mass spectrometry. Molecules such as 2-Oxazalidone; thiocyanic acid; Methanethioamide, N,N-dimethyl; 2-Coumaranone and other were characterizated. These results may consolidate traditional use of Trichilia gilgiana in pest management.
Symbiont Diversity of Zooxanthellae (Symbiodinium spp.) in Porites astreoides and Montastraea cavernosa from a Reciprocal Transplant in the Lower Florida Keys
Authors: Hauff Briana , Haslun Joshua A. , Strychar Kevin B. , Ostrom Peggy H. , Cervino James M.
Published: February 2016

In recent years, coral reefs worldwide have suffered high mortality rates due to coral bleaching, a phenomenon contributing to a 40% decrease in coral cover in the Florida Keys since the 1997/98 El Niño event. In the Florida Keys, coral from inshore reefs are known to be more thermotolerant than their conspecifics from offshore reefs but the mechanism behind this difference is unclear. In this study we conducted a two-year, reciprocal transplant of Porites astreoides and Montastraea cavernosa from an inshore and offshore reef in the lower Florida Keys to determine if changes in the dominant symbiotic algae (Symbiodinium spp.) could explain variation in holobiont tolerance as well as to assess the possibility of acclimatization to a changing stress regime. Increased complexity and diversity was demonstrated in the composition of Symbiodinium spp. from both coral species collected at the offshore reef when compared to conspecifics collected inshore. As a result of this complexity, the offshore reef samples displayed higher numbers of transitions of zooxanthellae subclade types between seasons, while inshore fragments demonstrated more stability and may explain previously measured thermotolerance. Additionally, the known thermotolerant subclade type D1 was associated with one M. cavernosa fragment from the inshore reef. When fragments were transplanted, compositional patterns of Symbiodinium spp. were retained from site of collection, indicating a lack of acclimatization to a new environment over the lengthy two-year experiment. These results demonstrate variability in the dominant Symbiodinium spp. of P. astreoides and M. cavernosa conspecifics from inshore and offshore reefs in the lower Florida Keys and point to possible patterns in holobiont thermotolerance. This variability may be key to the continued persistence of these species in the face of climate change, but future studies are needed to determine the mechanisms and range in which these subclade types withstand thermal stress.
Kumaraswamy Transmuted Exponentiated Additive Weibull Distribution
Authors: Nofal Zohdy M. , Afify Ahmed Z. , Yousof Haitham M. , Granzotto Daniele C. T. , Louzada Francisco
Published: February 2016

This paper introduces a new lifetime model which is a generalization of the transmuted exponentiated additive Weibull distribution by using the Kumaraswamy generalized (Kw-G) distribution. With the particular case no less than \textbf{seventy nine} sub models as special cases, the so-called Kumaraswamy transmuted exponentiated additive Weibull distribution, introduced by Cordeiro and de Castro (2011) is one of this particular cases. Further, expressions for several probabilistic measures are provided, such as probability density function, hazard function, moments, quantile function, mean, variance and median, moment generation function, R\'{e}nyi and q entropies, order estatistics, etc. Inference is maximum likelihood based and the usefulness of the model is showed by using a real dataset.
Hierarchical Motion Control for a Team of Humanoid Soccer Robots
Authors: Yi Seung-Joon , McGill Stephen , Hong Dennis , Lee Daniel
Published: February 2016

Robot soccer has become an effective benchmarking problem for robotics research as it requires many aspects of robotics including perception, self localization, motion planning and distributed coordination to work in uncertain and adversarial environments. Especially with humanoid robots that lack inherent stability, a capable and robust motion controller is crucial for generating walking and kicking motions without losing balance. In this paper, we describe the details of a motion controller to control a team of humanoid soccer robots, which consists of a hierarchy of controllers with different time frames and abstraction levels. A low level controller governs the real time control of each joint angle, either using target joint angles or target endpoint transforms. A mid-level controller handles bipedal locomotion and balancing of the robot. A high level controller decides the long term behavior of the robot, and finally the team level controller coordinates the behavior of a group of robots by means of asynchronous communication between the robots. The suggested motion system has been successfully used by many humanoid robot teams at the RoboCup international robot soccer competitions, which has awarded us five successful championships in a row.
Stable Walking of Humanoid Robots Using Vertical Center of Mass and Foot Motions by an Evolutionary Optimized Central Pattern Generator
Authors: Hong Young-Dae , Lee Ki-Baek
Published: February 2016

This paper proposes a method to produce the stable walking of humanoid robots by incorporating the vertical center of mass (COM) and foot motions, which are generated by the evolutionary optimized central pattern generator (CPG), into the modifiable walking pattern generator (MWPG). The MWPG extends the conventional 3-D linear inverted pendulum model (3-D LIPM) by allowing a zero moment point (ZMP) variation. The disturbance caused by the vertical COM motion is compensated in real time by the sensory feedback in the CPG. In this paper, the vertical foot trajectory of the swinging leg, as well as the vertical COM trajectory of the 3-D LIPM, are generated by the CPG for the effective compensation of the disturbance. Consequently, using the proposed method, the humanoid robot is able to walk with a vertical COM and the foot motions generated by the CPG, while modifying its walking patterns by using the MWPG in real time. The CPG with the sensory feedback is optimized to obtain the desired output signals. The optimization of the CPG is formulated as a constrained optimization problem with equality constraints and is solved by two-phase evolutionary programming (TPEP). The validity of the proposed method is verified through walking experiments for the small-sized humanoid robot, HanSaRam-IX (HSR-IX).
Designing a Novel Three-Degree-of-Freedom Parallel Robot Based on Workspace
Authors: Fu Jianxun , Gao Feng
Published: February 2016

This paper presents a novel three-degree-of-freedom (3-DOF) parallel manipulator and introduces its mechanical structure. Analytical solutions of the forward kinematics have been worked out, and all configurations of this robot are graphically displayed. On the basis of several special positions in the kinematics, a task workspace is prescribed to find the smallest feasible dimensional parameters of the robot. An algorithm describing this method is also introduced. This method can easily find appropriate parameters that can size a robot having the smallest workspace enclosing a predefined task workspace. This improves the design efficiency and ensures that the robot has a small mechanical size possessing a large workspace volume and, in terms of dimension design, meets the lightweight-design requirements. With examples illustrating the design results, we further introduce a design stability in dextoensure that the robot remains a safe distance from the boundary of its actual workspace. One prototype of the robot has already been developed.
Contour Detection-Based Discovery of Mid-Level Discriminative Patches for Scene Classification
Authors: Yang Jinfu , Zhang Jizhao , Wang Guanghui , Li Mingai
Published: February 2016

Feature extraction and representation is a key step in scene classification. In this paper, a contour detection-based mid-level features learning method is proposed for scene classification. First, a sketch tokens-based contour detection scheme is proposed to initialize seed blocks for learning mid-level patches and the patches with more contour pixels are selected as seed blocks. The procedure is demonstrated to be helpful for scene classification. Next, the seed blocks are employed to train an exemplar SVM to discover other similar occurrences and an entropy-rank criterion is utilized to mine the discriminative patches. Finally, scene categories are identified by matching the discriminative patches and testing images. Extensive experiments on the MIT Indoor-67 dataset, the 15-scene dataset and the UIUC-sports dataset show that the proposed approach yields better performance than other state-of-the-art counterparts.
Heading Control for a Robotic Dolphin Based on a Self-Tuning Fuzzy Strategy
Authors: Cao Zhiqiang , Shen Fei , Zhou Chao , Gu Nong , Nahavandi Saeid , Xu De
Published: February 2016

In this paper, a heading controller based on a self-tuning fuzzy strategy for a robotic dolphin is proposed to improve control accuracy and stability. The structure of the robotic dolphin is introduced and the turning motion is analysed. The analytic model indicates that the turning joint angle can be employed for the heading control. This non-linear model prevents the successful application of traditional model-based controllers. A fuzzy controller is proposed to realize the heading control in our work. It should be mentioned that the traditional fuzzy controller suffers from a distinguished steady-state error, due to the fact that the heading range is relatively large and the fuzzy controller's universe of discourse is fixed. To resolve this problem, a self-tuning mechanism is employed to adjust the input and output scaling factors according to the active working region in pursuit of favourable performance. Experimental results demonstrate the performance of the proposed controller in terms of steady-state error and robustness to interferences.
Metastatic papillary thyroid carcinoma to the nose: report and review of cutaneous metastases of papillary thyroid cancer
Authors: Cohen Philip R.
Published: February 2016

Background: Metastatic papillary thyroid carcinoma typically appears in local lymph nodes. Skin metastases are rare.

Purpose: A man with progressive metastatic papillary thyroid carcinoma who developed a cutaneous metastasis on his nose is described. The clinical manifestations of metastatic papillary thyroid carcinoma to skin are reviewed.

Methods: PubMed was used to search the following terms, separately and in combination: basal, cancer, carcinoma, cell, cutaneous, kinase, inhibitor, metastases, nose, papillary, rearranged during transfection, receptor, RET, thyroid, tyrosine, vandetanib.

Results: Pathologic changes observed on the biopsy of the man’s nose lesion were similar to those of his original cancer. Genomic evaluation of the tumor revealed an aberration involving the rearranged during transfection (RET) receptor tyrosine kinase. The residual tumor was excised. Treatment with vandetanib, a RET inhibitor was initiated; his metastatic disease has been stable, without symptoms or recurrent cutaneous metastasis, for 2 years following the discovery of his metastatic nose tumor.

Conclusions: Papillary thyroid carcinoma with skin metastases is rare. Nodules usually appear on the scalp or neck; the thyroidectomy scar is also a common site. Metastatic tumor, albeit infrequently, can present as a nose lesion. The prognosis for patients with cutaneous metastases from papillary thyroid carcinoma is poor. However, with the ability to test the tumor for genomic aberrations, molecular targeted therapies—such as tyrosine kinase inhibitors—may provide extended survival in these individuals.
Oral and written counseling is a useful instrument to improve short-term adherence to treatment in acne patients: a randomized controlled trial
Authors: Navarrete-Dechent Cristian Patricio , Curi-Tuma Maximiliano , Nicklas Claudia , Cárdenas Consuelo , Pérez-Cotapos María Luisa , Salomone Claudia
Published: February 2016

Background: Therapeutic success in acne patients not only depends in the appropriate selection of drugs but also on patient’s treatment adherence or compliance. Lack of adherence is a very important problem both in general medicine and in dermatologic practice.
Objective: To evaluate the impact of oral and written counseling in adherence to treatment in acne patients.
Patients and Methods: Eighty patients were randomized into a two study groups of 40 patients each in which instructions were given in a written note (besides oral counseling) and reinforced by a telephone within 15 days of onset, and a control group that received indications as usual (oral counseling in-office only). Both groups were followed-up, evaluating adherence to treatment according to self-reporting of patients at 30, 60, 90 days and 6 months.
Results: Better adherence to treatment was observed in the intervention group, being statistically significant only in the first month of treatment (80% versus 62%, p = 0.043). The beneficial effect of written counseling plus a phone call diluted in subsequent months.
Conclusion: Written counseling significantly improves adherence in the first month of treatment. Good adherence could also lead to more effective treatments so it seems reasonable to use time and resources to optimize adherence to treatment.
Dermoscopic findings in different clinical variants of lichen planus. Is dermoscopy useful?
Authors: Friedman Paula , Cohen Sabban Emilia , Marcucci Carolina , Peralta Rosario , Cabo Horacio
Published: February 2016

Lichen planus (LP) is a papulosquamous dermatosis that involves the skin, scalp, nails and mucous membranes. Although its pathogenesis is still unknown, there is evidence that an imbalance of immunologic cellular reactivity plays an important role. Histopathologic examination reveals characteristic interface dermatitis.

Dermoscopy is a non-invasive tool, useful in the assessment of inflammatory dermatoses, such as lichen planus. In this paper we describe the dermoscopic findings of different variants of LP (ungual, cutaneous, planopilaris, pigmentosus).
Next-Generation Sequencing Informatics: Challenges and Strategies for Implementation in a Clinical Environment
Authors: Roy Somak , LaFramboise William A. , Nikiforov Yuri E. , Nikiforova Marina N. , Routbort Mark J. , Pfeifer John , Nagarajan Rakesh , Carter Alexis B. , Pantanowitz Liron
Published: February 2016

Context.—Next-generation sequencing (NGS) is revolutionizing the discipline of laboratory medicine, with a deep and direct impact on patient care. Although it empowers clinical laboratories with unprecedented genomic sequencing capability, NGS has brought along obvious and obtrusive informatics challenges. Bioinformatics and clinical informatics are separate disciplines with typically a small degree of overlap, but they have been brought together by the enthusiastic adoption of NGS in clinical laboratories. The result has been a collaborative environment for the development of novel informatics solutions. Sustaining NGS-based testing in a regulated clinical environment requires institutional support to build and maintain a practical, robust, scalable, secure, and cost-effective informatics infrastructure.

Objective.—To discuss the novel NGS informatics challenges facing pathology laboratories today and offer solutions and future developments to address these obstacles.

Data Sources.—The published literature pertaining to NGS informatics was reviewed. The coauthors, experts in the fields of molecular pathology, precision medicine, and pathology informatics, also contributed their experiences.

Conclusions.—The boundary between bioinformatics and clinical informatics has significantly blurred with the introduction of NGS into clinical molecular laboratories. Next-generation sequencing technology and the data derived from these tests, if managed well in the clinical laboratory, will redefine the practice of medicine. In order to sustain this progress, adoption of smart computing technology will be essential. Computational pathologists will be expected to play a major role in rendering diagnostic and theranostic services by leveraging “Big Data” and modern computing tools.
Seguridad quirúrgica y cumplimentación del registro de información intraquirúrgica en España: Un análisis comparativo de dos instrumentos de registro
Authors: Torres Manrique Blanca , Nolasco Andreu , Maciá Loreto , Cervera A , Seva Llor Ana Myriam , Barberá Carmen
Published: February 2016

El objetivo del presente estudio es describir y comparar los porcentajes de no cumplimentación de dos instrumentos de registro: hoja circulante (HC) y lista de verificación quirúrgica (LVQ), en un mismo entorno quirúrgico para una muestra de pacientes de características similares.

Metodología: Estudio descriptivo realizado sobre registros intraquirúrgicos de 3024 pacientes de Cirugía de Ortopedia y Traumatología. 1732 pacientes intervenidos en 2009 con modelo de hoja circulante, cumplimentada al finalizar la intervención y 1292 en 2010 intervenidos con modelo de registro lista de verificación quirúrgica (checklist) cumplimentado durante la intervención en tres tiempos. Se han calculado características descriptivas (media, desviación típica, mínimo y máximo) del porcentaje de no cumplimentación global en ambos registros y el porcentaje de no cumplimentación (intervalo de confianza al 95%) de cada ítem de los registros estudiados.

Resultados: Se observa mayor porcentaje de cumplimentación global y, en general, también individual, en la hoja circulante que en la lista de verificación quirúrgica.
Conclusiones: El registro intraquirúrgico que mayor porcentaje de cumplimentación ha tenido de manera global ha sido la hoja de circulante y se evidencia la necesidad de implantar estrategias para mejorar el grado de cumplimentación de la LVQ por su relación con la seguridad de pacientes.
La gestión de los cuidados enfermeros en el hospital San Juan de Dios de Alicante: a propósito de tres fuentes documentales inéditas del siglo XVIII
Authors: Núñez del Castillo Mercedes , Vizcaya Moreno M Flores , Pérez Cañaveras Rosa María
Published: February 2016

Se propone como objetivo principal mostrar y analizar tres fuentes documentales inéditas del siglo XVIII, localizadas en el Archivo Municipal Sant Joan d’Alacant que aportan información sobre la gestión de enfermería realizada en el Hospital San Juan de Dios de Alicante. Son tres las fuentes documentales que se transcriben y analizan, una “relación jurada de Fray Joseph Martínez Maza”, fechando el documento entre 1710 y 1718; un “Real privilegio de S.M. para amortizar la cantidad de 120 libras libres de sello y demás”. Dado en 23 de enero de 1794, a favor del convento hospital de N.P. San Juan de Dios de la ciudad de Alicante y un “formulario o modelo para dar cumplimiento a la orden del nuncio de su Santidad referente a las rentas, gravámenes, limosnas y otras entradas, con la curación a pobres, enfermos, con arreglo a los libros de caja”, datando el documento entre 1748 y 1760.
Instrumentos e fatores impactantes sobre o conhecimento das medidas de precauções-padrão entre trabalhadores de saúde
Authors: Valim Marília Duarte , De Morais Richarlisson Borges , Marziale Maria Helena Palucci
Published: February 2016

El objetivo fue identificar instrumentos para medir el conocimiento y la información de los profesionales de la salud acerca de las precauciones estándar (PE); describir estos conocimientos; verificar las dimensiones y contenidos valorados; informar sus características psicométricas y los factores que influyen en el conocimiento.

Revisión integral, cuyas palabras-clave fueran buscadas en base de datos Lilacs, Pubmed (Medline), ISI Web of Knowledge, Scopus y CINAHL. La muestra final fue 18 estudios transversales, heterogéneos en cuanto a los sitios y sectores de ejecución, así como los países situados en las diversas clasificaciones del Índice de Desarrollo Humano. Ningún instrumento incluyó todos los tópicos recomendados y la validación de contenido fue la mayor preocupación de los autores. El conocimiento está por debajo de lo recomendado y la mayoría no comprende los objetivos de las PE. Se sugiere la validación de los instrumentos existentes para obtener resultados confiables.
Lambda-Lifting in Quadratic Time
Authors: Danvy Olivier , Schultz Ulrik P.
Published: February 2016

Lambda-lifting is a program transformation used in compilers and in partial evaluators and that operates in cubic time. In this article, we show how to reduce this complexity to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time.

Lambda-lifting transforms a block-structured program into a set of recursive equations, one for each local function in the source program. Each equation carries extra parameters to account for the free variables of the corresponding local function and of all its callees. It is the search for these extra parameters that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by a transitive closure.

Instead, we partition the call graph of the source program into strongly connected components, based on the simple observation that all functions in each component need the same extra parameters and thus a transitive closure is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity of lambda-lifting from O(n^3 log n) to O(n^2 log n), where n is the size of the program.

Since a lambda-lifter can output programs of size O(n^2), we believe that our algorithm is close to optimal.
Nested Semantics over Finite Trees are Equationally Hard
Authors: Aceto Luca , Fokkink Willem Jan , Glabbeek Rob J. van , Ingólfsdóttir Anna
Published: February 2016

This paper studies nested simulation and nested trace semantics over the language BCCSP, a basic formalism to express finite process behaviour. It is shown that none of these semantics affords finite (in)equational axiomatizations over BCCSP. In particular, for each of the nested semantics studied in this paper, the collection of sound, closed (in)equations over a singleton action set is not finitely based.
Computational Collapse of Quantum State with Application to Oblivious Transfer
Authors: Crépeau Claude , Dumais Paul , Mayers Dominic , Salvail Louis
Published: February 2016

Quantum 2-party cryptography differs from its classical counterpart in at least one important way: Given black-box access to a perfect commitment scheme there exists a secure 1-2 quantum oblivious transfer. This reduction proposed by Crépeau and Kilian was proved secure against any receiver by Yao, in the case where perfect commitments are used. However, quantum commitments would normally be based on computational assumptions. A natural question therefore arises: What happens to the security of the above reduction when computationally secure commitments are used instead of perfect ones?

In this paper, we address the security of 1-2 QOT when computationally binding string commitments are available. In particular, we analyse the security of a primitive called Quantum Measurement Commitment when it is constructed from unconditionally concealing but computationally binding commitments. As measuring a quantum state induces an irreversible collapse, we describe a QMC as an instance of ``computational collapse of a quantum state''. In a QMC a state appears to be collapsed to a polynomial time observer who cannot extract full information about the state without breaking a computational assumption.

We reduce the security of QMC to a weak binding criteria for the string commitment. We also show that secure QMCs implies QOT using a straightforward variant of the reduction above.
Applying pi-Calculus to Practice: An Example of a Unified Security Mechanism
Authors: Abendroth Jörg
Published: February 2016

The Pi-calculus has been developed to reason about behavioural equivalence. Different notions of equivalence are defined in terms of process interactions, as well as the context of processes. There are various extensions of the Pi-calculus, such as the SPI calculus, which has primitives to facilitate security protocol design.

Another area of computer security is access control research, which includes problems of access control models, policies and access control mechanism. The design of a unified framework for access control requires that all policies are supported and different access control models are instantiated correctly.

In this paper we will utilise the Pi calculus to reason about access control policies and mechanism. An equivalence of different policy implementations, as well as access control mechanism will be shown. Finally some experiences regarding the use of Pi-calculus are presented.
Domain Theory for Concurrency
Authors: Nygaard Mikkel , Winskel Glynn
Published: February 2016

A simple domain theory for concurrency is presented. Based on a categorical model of linear logic and associated comonads, it highlights the role of linearity in concurrent computation. Two choices of comonad yield two expressive metalanguages for higher-order processes, both arising from canonical constructions in the model. Their denotational semantics are fully abstract with respect to contextual equivalence. One language derives from an exponential of linear logic; it supports a straightforward operational semantics with simple proofs of soundness and adequacy. The other choice of comonad yields a model of affine-linear logic, and a process language with a tensor operation to be understood as a parallel composition of independent processes. The domain theory can be generalised to presheaf models, providing a more refined treatment of nondeterministic branching. The article concludes with a discussion of a broader programme of research, towards a fully fledged domain theory for concurrency.
Composing Programming Languages by Combining Action-Semantics Modules
Authors: Doh Kyung-Goo , Mosses Peter D.
Published: February 2016

This article demonstrates a method for composing a programming language by combining action-semantics modules. Each module is defined separately, and then a programming-language module is defined by combining existing modules. This method enables the language designer to gradually develop a language by defining, selecting and combining suitable modules. The resulting modular structure is substantially different from that previously employed in action-semantic descriptions.

It also discusses how to resolve the conflicts that may arise when combining modules, and indicates some advantages that action semantics has over other approaches in this respect.
An Extended Quadratic Frobenius Primality Test with Average and Worst Case Error Estimates
Authors: Damgård Ivan B. , Frandsen Gudmund Skovbjerg
Published: February 2016

We present an Extended Quadratic Frobenius Primality Test (EQFT), which is related to the Miller-Rabin test and the Quadratic Frobenius test (QFT) by Grantham. EQFT takes time about equivalent to 2 Miller-Rabin tests, but has much smaller error probability, namely 256/331776^t for t iterations of the test in the worst case. EQFT extends QFT by verifying additional algebraic properties related to the existence of elements of order dividing 24. We also give bounds on the average-case behaviour of the test: consider the algorithm that repeatedly chooses random odd k bit numbers, subjects them to t iterations of our test and outputs the first one found that passes all tests. We obtain numeric upper bounds for the error probability of this algorithm as well as a general closed expression bounding the error. For instance, it is at most 2^{-143} for k=500, t = 2. Compared to earlier similar results for the Miller-Rabin test, the results indicate that our test in the average case has the effect of 9 Miller-Rabin tests, while only taking time equivalent to about 2 such tests. We also give bounds for the error in case a prime is sought by incremental search from a random starting point.
Lambda-Lifting in Quadratic Time
Authors: Danvy Olivier , Schultz Ulrik P.
Published: February 2016

Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time.

Lambda-lifting transforms a block-structured program into a set of recursive equations, one for each local function in the source program. Each equation carries extra parameters to account for the free variables of the corresponding local function and of all its callees. It is the search for these extra parameters that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure.

To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based on the simple observation that all functions in each component need the same extra parameters and thus a transitive closure is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity of lambda-lifting from O(n^3) to O(n^2), where n is the size of the program.

Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal.
Profunctors, Open Maps and Bisimulation
Authors: Cattani Gian Luca , Winskel Glynn
Published: February 2016

This paper studies fundamental connections between profunctors (i.e., distributors, or bimodules), open maps and bisimulation. In particular, it proves that a colimit preserving functor between presheaf categories (corresponding to a profunctor) preserves open maps and open map bisimulation. Consequently, the composition of profunctors preserves open maps as 2-cells. A guiding idea is the view that profunctors, and colimit preserving functors, are linear maps in a model of classical linear logic. But profunctors, and colimit preserving functors, as linear maps, are too restrictive for many applications. This leads to a study of a range of pseudo-comonads and how non-linear maps in their co-Kleisli bicategories preserve open maps and bisimulation. The pseudo-comonads considered are based on finite colimit completion, ``lifting'', and indexed families. The paper includes an appendix summarising the key results on coends, left Kan extensions and the preservation of colimits. One motivation for this work is that it provides a mathematical framework for extending domain theory and denotational semantics of programming languages to the more intricate models, languages and equivalences found in concurrent computation. But the results are likely to have more general applicability because of the ubiquitous nature of profunctors.
A Functional Correspondence between Call-by-Need Evaluators and Lazy Abstract Machines
Authors: Ager Mads Sig , Danvy Olivier , Midtgaard Jan
Published: February 2016

We bridge the gap between compositional evaluators and abstract machines for the lambda-calculus, using closure conversion, transformation into continuation-passing style, and defunctionalization of continuations. This article is a followup of our article at PPDP 2003, where we consider call by name and call by value. Here, however, we consider call by need.

We derive a lazy abstract machine from an ordinary call-by-need evaluator that threads a heap of updatable cells. In this resulting abstract machine, the continuation fragment for updating a heap cell naturally appears as an `update marker', an implementation technique that was invented for the Three Instruction Machine and subsequently used to construct lazy variants of Krivine's abstract machine. Tuning the evaluator leads to other implementation techniques such as unboxed values. The correctness of the resulting abstract machines is a corollary of the correctness of the original evaluators and of the program transformations used in the derivation.
A Runtime System for XML Transformations in Java
Authors: Christensen Aske Simon , Kirkegaard Christian , Møller Anders
Published: February 2016

We show that it is possible to extend a general-purpose programming language with a convenient high-level data-type for manipulating XML documents while permitting (1) precise static analysis for guaranteeing validity of the constructed XML documents relative to the given DTD schemas, and (2) a runtime system where the operations can be performed efficiently. The system, named Xact, is based on a notion of immutable XML templates and uses XPath for deconstructing documents. A companion paper presents the program analysis; this paper focuses on the efficient runtime representation.
An Action Environment
Authors: Brand Mark Van den , Iversen Jørgen , Mosses Peter D.
Published: February 2016

Some basic programming constructs (e.g., conditional statements) are found in many different programming languages, and can often be included without change when a new language is designed. When writing a semantic description of a language, however, it is usually not possible to reuse parts of previous descriptions without change.

This paper introduces a new formalism, ASDF, which has been designed specifically for giving reusable action semantic descriptions of individual language constructs. An initial case study in the use of ASDF has already provided reusable descriptions of all the basic constructs underlying Core ML.

 The paper also describes the Action Environment, a new environment supporting use and validation of ASDF descriptions. The Action Environment has been implemented on top of the ASF+SDF Meta-Environment, exploiting recent advances in techniques for integration of different formalisms, and inheriting all the main features of the Meta-Environment.
Secure Computing, Economy, and Trust: A Generic Solution for Secure Auctions with Real-World Applications
Authors: Bogetoft Peter , Damgård Ivan B. , Jakobsen Thomas , Nielsen Kurt , Pagter Jakob , Toft Tomas
Published: February 2016

In this paper we consider the problem of constructing secure auctions based on techniques from modern cryptography. We combine knowledge from economics, cryptography and security engineering and develop and implement secure auctions for practical real-world problems.

In essence this paper is an overview of the research project SCET--Secure Computing, Economy, and Trust-- which attempts to build auctions for real applications using secure multiparty computation.

The main contributions of this project are: A generic setup for secure evaluation of integer arithmetic including comparisons; general double auctions expressed by such operations; a real world double auction tailored to the complexity and performance of the basic primitives '+' and '<='; and finally evidence that our approach is practically feasible based on experiments with prototypes.
Finite Equational Bases in Process Algebra: Results and Open Questions
Authors: Aceto Luca , Fokkink Willem Jan , Ingólfsdóttir Anna , Luttik Bas
Published: February 2016

Van Glabbeek (1990) presented the linear time-branching time spectrum of behavioral equivalences for finitely branching, concrete, sequential processes. He studied these semantics in the setting of the basic process algebra BCCSP, and tried to give finite complete and omega-complete axiomatizations for them. (An axiomatization E is omega-complete when an equation can be derived from E if, and only if, all its closed instantiations can be derived from E.) Obtaining such axiomatizations in concurrency theory often turns out to be difficult, even in the setting of simple languages like BCCSP. This has raised a host of open questions that have been the subject of intensive research in recent years. Most of these questions have been settled over BCCSP, either positively by giving a finite complete or omega-complete axiomatization, or negatively by proving that such an axiomatization does not exist. Still some open questions remain. This paper reports on these results, and on the state-of-the-art on axiomatizations for richer process algebras, containing constructs like sequential and parallel composition.
There and Back Again
Authors: Danvy Olivier , Goldberg Mayer
Published: February 2016

We present a programming pattern where a recursive function defined over a data structure traverses another data structure at return time. The idea is that the recursive calls get us `there' by traversing the first data structure and the returns get us `back again' while traversing the second data structure. We name this programming pattern of traversing a data structure at call time and another data structure at return time ``There And Back Again'' (TABA).

The TABA pattern directly applies to computing symbolic convolutions and to multiplying polynomials. It also blends well with other programming patterns such as dynamic programming and traversing a list at double speed. We illustrate TABA and dynamic programming with Catalan numbers. We illustrate TABA and traversing a list at double speed with palindromes and we obtain a novel solution to this traditional exercise. Finally, through a variety of tree traversals, we show how to apply TABA to other data structures than lists.

A TABA-based function written in direct style makes full use of an ALGOL-like control stack and needs no heap allocation. Conversely, in a TABA-based function written in continuation-passing style and recursively defined over a data structure (traversed at call time), the continuation acts as an iterator over a second data structure (traversed at return time). In general, the TABA pattern saves one from accumulating intermediate data structures at call time.
Type Checking with XML Schema in XACT
Authors: Kirkegaard Christian , Møller Anders
Published: February 2016

We show how to extend the program analysis technique used in the XACT system to support XML Schema as type formalism. Moreover, we introduce optional type annotations to improve modularity of the type checking. The resulting system supports a flexible style of programming XML transformations and provides static guarantees of validity of the generated XML data.
Extending the Extensional Lambda Calculus with Surjective Pairing is Conservative
Authors: Støvring Kristian
Published: February 2016

We answer Klop and de Vrijer's question whether adding surjective-pairing axioms to the extensional lambda calculus yields a conservative extension. The answer is positive. As a byproduct we obtain the first ``syntactic'' proof that the extensional lambda calculus with surjective pairing is consistent.
Static Analysis for Java Servlets and JSP
Authors: Kirkegaard Christian , Møller Anders
Published: February 2016

We present an approach for statically reasoning about the behavior of Web applications that are developed using Java Servlets and JSP. Specifically, we attack the problems of guaranteeing that all output is well-formed and valid XML and ensuring consistency of XHTML form fields and session state. Our approach builds on a collection of program analysis techniques developed earlier in the JWIG and XACT projects, combined with work on balanced context-free grammars. Together, this provides the necessary foundation concerning reasoning about output streams and application control flow.
A Dynamic Continuation-Passing Style for Dynamic Delimited Continuations
Authors: Biernacki Dariusz , Danvy Olivier , Millikin Kevin
Published: February 2016

We put a pre-existing definitional abstract machine for dynamic delimited continuations in defunctionalized form, and we present the consequences of this adjustment.

We first prove the correctness of the adjusted abstract machine. Because it is in defunctionalized form, we can refunctionalize it into a higher-order evaluation function. This evaluation function, which is compositional, is in continuation+state passing style and threads a trail of delimited continuations and a meta-continuation. Since this style accounts for dynamic delimited continuations, we refer to it as `dynamic continuation-passing style' and we present the corresponding dynamic CPS transformation. We show that the notion of computation induced by dynamic CPS takes the form of a continuation monad with a recursive answer type and we present a new simulation of dynamic delimited continuations in terms of static ones as well as new applications of dynamic delimited continuations.

The significance of the present work is that the computational artifacts surrounding dynamic CPS are not independent designs: they are mechanical consequences of having put the definitional abstract machine in defunctionalized form.
A Concrete Framework for Environment Machines
Authors: Biernacka Malgorzata , Danvy Olivier
Published: February 2016

We materialize the common understanding that calculi with explicit substitutions provide an intermediate step between an abstract specification of substitution in the lambda-calculus and its concrete implementations. To this end, we go back to Curien's original calculus of closures (an early calculus with explicit substitutions), we extend it minimally so that it can also express one-step reduction strategies, and we methodically derive a series of environment machines from the specification of two one-step reduction strategies for the lambda-calculus: normal order and applicative order. The derivation extends Danvy and Nielsen's refocusing-based construction of abstract machines with two new steps: one for coalescing two successive transitions into one, and the other for unfolding a closure into a term and an environment in the resulting abstract machine. The resulting environment machines include both the Krivine machine and the original version of Krivine's machine, Felleisen et al.'s CEK machine, and Leroy's Zinc abstract machine.
Analyzing Ambiguity of Context-Free Grammars
Authors: Brabrand Claus , Giegerich Robert , Møller Anders
Published: February 2016

It has been known since 1962 that the ambiguity problem for context-free grammars is undecidable. Ambiguity in context-free grammars is a recurring problem in language design and parser generation, as well as in applications where grammars are used as models of real-world physical structures. However, the fact that the problem is undecidable does not mean that there are no useful approximations to the problem.

We observe that there is a simple linguistic characterization of the grammar ambiguity problem, and we show how to exploit this to conservatively approximate the problem based on local regular approximations and grammar unfoldings. As an application, we consider grammars that occur in RNA analysis in bioinformatics, and we demonstrate that our static analysis of context-free grammars is sufficiently precise and efficient to be practically useful.

 

Full text: http://dx.doi.org/10.1016/j.scico.2009.11.002
An Investigation of Abadi and Cardelli's Untyped Calculus of Objects
Authors: Johannsen Jacob
Published: February 2016

We study the relationship between the natural (big-step) semantics and the reduction (small-step) semantics of Abadi and Cardelli's untyped calculus of objects. By applying Danvy et al.'s functional correspondence to the natural semantics, we derive an abstract machine for this calculus, and by applying Danvy et al.'s syntactic correspondence to the reduction semantics, we also derive an abstract machines for this calculus. These two abstract machines are identical. The fact that the machines are identical, and the fact that they have been derived using meaning-preserving program transformations, entail that the derivation constitutes a proof of equivalence between natural semantics and the reduction semantics. The derivational nature of our proof contrasts with Abadi and Cardelli's soundness proof, which was carried out by pen and paper. We also note that the abstract machine is new.

To move closer to actual language implementations, we reformulate the calculus to use explicit substitutions. The reformulated calculus is new. By applying the functional and syntactic correspondences to natural and reduction semantics of this new calculus, we again obtain two abstract machines. These two machines are also identical, and as such, they establish the equivalence of the natural semantics and the reduction semantics of the new calculus.

Finally, we prove that the two abstract machines are strongly bisimilar. Therefore, the two calculi are computationally equivalent.
Monadic Second-order Logic for Parameterized Verification
Authors: Jensen Jakob L. , Jørgensen Michael E. , Klarlund Nils
Published: February 2016

Much work in automatic verification considers families of similar finite-state systems. But an often overlooked property is that sometimes a single finite-state system can be used to describe a parameterized, infinite family of systems. Thus verification of unbounded state spaces can take place by reduction to finite ones.

The purpose of this article is to introduce Monadic Second-order Logic as a practical means of carrying out such reductions. The logic is a highly succinct alternative to the use of regular expressions. We have built a tool that acts as a decision procedure and translator to DFAs.

The potential applications are numerous. We discuss text processing, Boolean circuits, and distributed systems. Our main example is an automatic proof of properties for the ``Dining Philosophers with Encyclopedia'' example by Kurshan and MacMillan. We establish these properties for the parameterized case  without the use of induction.
Models for Concurrency
Authors: Winskel Glynn , Nielsen Mogens
Published: February 2016

This report surveys a range of models for parallel computation to include interleaving models like transition systems, synchronisation trees and languages (often called Hoare traces in this context), and models like Petri nets, asynchronous transition systems, event structures, pomsets and Mazurkiewicz traces where concurrency is represented more explicitly by a form of causal independence. The presentation is unified by casting the models in a category-theoretic framework. One aim is to use category theory to provide abstract characterisations of constructions like parallel composition valid throughout a range of different models and to provide formal means for translating between different models.

A knowledge of basic category theory is assumed, up to an acquaintance with the notion of adjunction.