bluuebunny/crossref_metadata_2025 huggingface dataset:
REKONSTRUKSI HUKUM ISLAM: KAJIAN HISTORIS ATAS URGENSI PELEMBAGAAN WAKAF PRODUKTIF DI INDONESIA
Authors: Syukron Ahmad
Published: January 2018

This paper studied the urgency of Islamic Law reconception, especially focused on productive wakaf (sustainable Islamic donation) management. As one of Islamic teaching, wakaf has two dimensions, individual and social. If it was worked and managed productively, wakaf would become one of economic power toward Muslims. Following this trend, the study tried to focus on problems of developing productive wakaf management teaching in Indonesia. This study was library research and used historical approach. In gathering data, it took secondary and primary ones, and then analyzed them inductively and deductively, simultaneously
PERSEPSI MASYARAKAT PENGGUNA TERHADAP KOMPETENSI ALUMNI JURUSAN TARBIYAH STAIN PEKALONGAN
Authors: Karyanto Umum B.
Published: January 2018

This study aims to describe users’ perception on the competencies of STAIN Pekalongan Tarbiyah Programs’ alumni, namely those who devote themselves into the world of education. Teachers and lecturers should be able to fulfill the four competencies, namely (1) pedagogical competence, (2) competence of personality, (3) social competence, and (4) professional competence. These competencies are comprehensive and constitute an integral and interconnected with each other and support each other. Descriptive statistics was employed to analize the data. Research results indicate that (1) users’ perception on alumni’s pedagogical competence are above average which 77% schools on Kemdiknas’ oversight rate them as good, as well as 73% schools on Depag’s oversight (2) users’ perception on alumni’s personal competency/personality are above average which 81% schools on Kemdiknas’ oversight rate them as good, as well as 78% schools on Depag’s oversight (3) users’ perception on alumni’s social competency are above average which 75% schools on Kemdiknas’ oversight rate them as good, as well as 74% schools on Depag’s oversight; and (4) users’ perception on alumni’s professional competency are above average which 76% schools on Kemdiknas’ oversight rate them as good, as well as 73% schools on Depag’s oversight. Thus, it can be concluded that both users rate them as good and competence
Correcciones atmosféricas relativas de imágenes de satélite: patrones invariantes y modelos atmosféricos
Authors: Paz Pellat Fernando
Published: January 2018

To use information obtained with satellite technology reliably, it is necessary to eliminate or reduce the disruptive effects associated with the spectral information captured by sensors on space platforms. In this paper we analyze the inversion of radiative models of the atmosphere, which consists in determining the additive and multiplicative constants in each spectral band to make the necessary atmospheric corrections. The methodology proposes the use of invariant patterns of soil lines and dense vegetation for the inversion of radiative models. The results showed that, without knowledge of the atmospheric model or the type of aerosol, soil line data were relatively insufficient (low correlation) to obtain the additive and multiplicative constants of the atmospheric inversions, with problems of multiple solutions in the inversion process. Under similar conditions, the same was found for additive constants with the dense vegetation line, but for the multiplicative constants the results were favorable (R2 > 0.9). In contrast, with the knowledge of the atmospheric model and the aerosol model, estimates of additive and multiplicative constants were highly satisfactory (R2 > 0.99) in both cases. For soil line inversions, only one constraint of the two available was used. In conclusion, the use of invariant soil-line patterns allows us to establish two basic relationships to invert the radiative simulations of the atmosphere, prior to functional compaction, and field measurements can be made so that the proposed atmospheric correction process in this work can be considered in absolute and not relative terms.
Corrección de la clorosis férrica con quelato EDDHA en cultivos sembrados en suelo alcalino y calcáreo
Authors: DIAZ FRANCO ARTURO , ESPINOSA RAMIREZ MARTIN , ORTIZ CHÁIREZ FLOR ELENA
Published: January 2018

Iron deficiency in crops occurs mainly in regions with alkaline and calcareous soils. In the present study the effectiveness of Fe3+ chelated EDDHA [ethylenediamine di-(o-hydroxyphenylacetic acid)] is assessed alone or combined with foliar spray of FeSO4, in crops of sorghum, soybean, okra and beans. EDDHA-Fe (Ultraferro®) was applied at a dose of 1% on the seed at sowing and FeSO4 was applied on foliage twice at 1.5%. In the four experiments, we determined the variables index of chlorophyll (SPAD) in three readings (March 15 and 28, April 6), and 47-50 days after sowing and leaf and root biomass. Between crops, soybeans and okra expressed greater intensity of chlorosis, which was visible among treatments. In both crops, higher SPAD and leaf and root biomass values were obtained with applications of EDDHA-Fe alone or combined with FeSO4. In okra, the SPAD index was higher with the combination EDDHA-Fe + FeSO4, although root and leaf biomass was greater with EDDHA-Fe alone or in combination with FeSO4. In beans and sorghum, chlorosis was less visible. For beans, the highest SPAD rate was recorded with EDDHA-Fe and/or FeSO4 in the two latest readings (March 28 and April 6) and in leaf and root biomass. Similarly, the three chemical treatments exceeded the control. However, in sorghum, the highest SPAD was recorded on the last reading (Apr-6), while there were no significant differences in leaf and root biomass. There were no observed additive effects on the variables with the combination EDDHA-Fe and FeSO4. In general, the results indicate that application of EDDHA-Fe alone or combined with foliar FeSO4 in soybean, okra and bean, effectively corrected chlorosis ferric.
Familias de agua subterránea y distribución de sólidos totales disueltos en el acuífero de La Paz Baja California Sur, México
Authors: Cruz Falcón Arturo , Troyo Diéguez Enrique , Murillo Jiménez Janette M. , García Hernández José Luis , Murillo Amador Bernardo
Published: January 2018

The aquifer of La Paz has been overexploited for several years, causing contamination by seawater intrusion. A well-monitoring network, which included public-urban, agricultural, livestock and service use water wells, was set up in 2013. Representative sampling during the dry and rainy seasons was carried out. Concentration of total dissolved solids (TDS), temperature, dissolved oxygen and pH were measured. Results indicate that most agricultural wells contain high TDS concentration, compared to potable water wells with concentration below 1000 mg L-1, which is the limit allowed by the Mexican official standard (MOS). Majority ion data from 14 wells near the coast with high concentration of TDS were also analyzed, with which a Piper diagram was constructed. Two main types of water were found: calcium-chloride and sodium-chloride. The presence of sodium in concentrations exceeding 200 mg L-1 in 8 wells, and magnesium with more than 50 mg L-1 in 10 wells, both above the MOS, reveal that its origin is seawater. Calcium concentrations above 250 mg L‑1 in 7 wells points to the existence of sedimentary layers of chemical-organic origin that compose the inner stratigraphy of the aquifer through which groundwater circulates. High chloride concentrations of more than 1000 mg L-1 in 6 wells with high concentration of TDS, suggests that its source is seawater intrusion. Based on the distribution of TDS concentration, two broad areas affected by seawater intrusion were delimited, and along with the distribution of water families, three main aquifer zones were identified.
Interaction microenvironment - Pantoea agglomerans limits maize yield
Authors: Ruíz Juárez Daniel , Azaola Espinosa Alejandro , Esquivel Esquivel Gilberto , Segundo Pedraza Eva , Silva Rojas Hilda Victoria
Published: January 2018

Pantoea agglomerans has been reported as the cause of chlorotic streaks on maize leaves in the Central High Valleys of México (CVHM), but there are no current data of how the infection of this new pathogen in Mexico affects production and yield of the crop. To understand the development of the disease in the crop, two experiments with a split-plot design and three replications were established during spring-summer 2010 in different microenvironments: Ayapango and Temamatla. Three cultivars of maize (a tri-linear HS2 hybrid, the single-cross hybrid Triunfo and the native Cacahuacintle) were evaluated with three P. agglomerans isolates. In the three maize cultivars, chlorotic streaks appeared on new leaves; at the ripening stage, the symptoms were less perceptible. The average incidence of plants with chlorotic streaks was higher in the town of Temamatla than in Ayapango, and in both microenvironments, the average degree of severity was less than 40%. Isolate A was the most virulent (P < 0.0001) on the three cultivars evaluated. These results will provide the basis for effective management of the disease under environmental conditions similar to those evaluated in this research.
Analyzable Legal Yes/No Question Answering System using Linguistic Structures
Authors: Kano Yoshinobu , Hoshino Reina , Taniguchi Ryosuke
Published: January 2018

A central issue of yes/no question answering is usage of knowledge source given a question. While yes/no question answering has been studied for a long time, legal yes/no question answering largely differs from other domains. The most distinguishing characteristic is that legal issues require precise linguistic analysis such as predicates, case-roles, conditions, etc. We have developed a yes/no question answer-ing system for answering questions in a legal domain. Our system uses linguistic analysis, in order to find correspondences of predicates and arguments given problem sentences and knowledge source sentences. We applied our system to the COLIEE (Competition on Legal Information Extraction/Entailment) 2017 task. Our team shared the second place in this COLIEE 2017 Phase Two task, which asks to answer yes or no given a problem sentence. This result shows that precise linguistic analyses are effective even without the big data approach with machine learning, rather better in its analyzable design for future improvements.
Benchmark problem: an air brake model for trains
Authors: Parolini Luca , Schuler Simone , Anta Adolfo
Published: January 2018

This paper proposes a simplified hybrid model of a freight train equipped with an air brake. The control of such a system and the enforcement of numerous safety constraints constitute a relevant benchmark to evaluate tools for proving safety requirements in hybrid systems.
MetTeL2: Towards a Tableau Prover Generation Platform
Authors: Tishkovsky Dmitry , Schmidt Renate A. , Khodadadi Mohammad
Published: January 2018

This paper introduces MetTeL2, a tableau prover generator producing Java code from the specifications of a logical syntax and a tableau calculus. It is intended to provide an easy to use system for non-technical users and allow technical users to extend the generated implementations.
Flow* 1.2: More Effective to Play with Hybrid Systems
Authors: Chen Xin , Sankaranarayanan Sriram , Abraham Erika
Published: January 2018

This paper gives a brief overview of the new features introduced in the latest version of the tool Flow*. We mainly describe the new efficient scheme for integrating linear ODEs. We show that it can efficiently handle the challenging benchmarks on which, to the best of our knowledge, only SpaceEx works. Moreover, it is also possible to extend the method to deal with unbounded initial sets. A comparison between Flow* 1.2 and SpaceEx on those benchmarks is given. Besides, we also investigate the scalability Flow* 1.2 based on our non-linear line circuit benchmarks.
Symbolic-Numeric Reachability Analysis of Hybrid Systems
Authors: Sankaranarayanan Sriram
Published: January 2018

We consider the problem of reachability analysis in hybrid systems defined by the closed-loop interaction of a complex, continuous time plant model with a software-based controller. In practice, the plant model is, often, a coarse approximation of the real-world operating environment of the software, whereas the software itself is the artifact that ends up being deployed in the final system. In this talk, we summarize the state-of-the-art techniques for purely symbolic and purely numeric approaches to reachability analysis of hybrid systems. We make the case for approaches that combine simulation-based exploration of the plant state-space with a corresponding symbolic exploration of the controller. We propose a simple yet elegant method to carry out this joint symbolic-numeric exploration based on an abstraction of the plant model, and present promising experimental results on software-in-the-loop setups that are beyond the scope of many existing verification tools.
Benchmark Generator for Stratified Controllers of Tank Networks
Authors: Bak Stanley , Bogomolov Sergiy , Greitschus Marius , Johnson Taylor T
Published: January 2018

We present a new model of a tank network used to transfer liquid. Tanks are connected by channels. The throughput velocity of every particular channel is governed by the controller. We consider a special class of stratified controllers which are organized in several phases. Every phase can be further partitioned into multiple options. This structure makes it easy to generate a variety of benchmark instances ranging in the size, branching factor and generally analysis complexity. We provide a flexible benchmark generator for this class of benchmarks and a sample benchmark suite built by the generator. Finally, we use the Hyst model transformation framework to convert the original model in a format compatible with several reachability tools.
Towards an Expressive Practical Logical Action Theory
Authors: Soutchanski Mikhail , Yehia Wael
Published: January 2018

In the area of reasoning about actions, one of the key computational problems is the projection problem: to find whether a given logical formula is true after

performing a sequence of actions. This problem is undecidable in the general

situation calculus; however, it is decidable in some fragments. We consider

a fragment P of the situation calculus and Reiter's basic action theories (BAT)

such that the projection problem can be reduced to the satisfiability problem

in an expressive description logic $ALCO(U)$ that includes nominals ($O$),

the universal role ($U$), and constructs from the well-known logic $ALC$. It turns out

that our fragment P is more expressive than previously explored description logic

based fragments of the situation calculus. We explore some of the logical properties of our theories.

In particular, we show that the projection problem can be solved using regression

in the case where BATs include a general ``static" TBox, i.e., an ontology that has

no occurrences of fluents. Thus, we propose seamless integration of traditional

ontologies with reasoning about actions. We also show that the projection

problem can be solved using progression if all actions have only local effects on

the fluents, i.e., in P, if one starts with an incomplete initial theory that

can be transformed into an $ALCO(U)$ concept, then its progression resulting from

execution of a ground action can still be expressed in the same language. Moreover,

we show that for a broad class of incomplete initial theories progression can be computed efficiently.
Djinn, Monotonic
Authors: McBride Conor
Published: January 2018

Dyckhoff's algorithm for contraction-free proof search in intuitionistic propositional logic (popularized by Augustsson as the type-directed program synthesis tool, Djinn) is a simple program with a rather tricky termination proof. In this talk, I describe my efforts to reduce this program to a steady structural descent. On the way, I shall present an attempt at a compositional approach to explaining termination, via a uniform presentation of memoization.
A general framework for geometric dualities for varieties of algebras
Authors: Spada Luca
Published: January 2018

We set up a framework that subsumes many important dualities in mathematics (Birkhoff, Stone, Priestly, Baker-Beynon, etc.) as well as the classical correspondence between polynomial ideals and affine varieties in algebraic geometry. Our main theorems provide a generalisation of Hilbert's Nullstellensatz to any (possibly infinitary) variety of algebras. The common core of the above dualities becomes then clearly visible and sets the basis to a canonical method to seek for a geometric dual to any given variety of algebras.
A Complete Calculus of Monotone and Antitone Higher-Order Functions
Authors: Icard Thomas , Moss Lawrence
Published: January 2018

This paper adds monotonicity and antitonicity information to the typed lambda calculus, thereby providing a foundation for the Monotonicity Calculus first developed by van Benthem and others. We establish properties of the type system, propose a syntax, semantics, and proof calculus, and prove completeness for the calculus with respect to hierarchies of monotone and antitone functions over base preorders.
Improving SAT Solver Performance with Structure-based Preferential Bumping
Authors: Jamali Sima , Mitchell David
Published: January 2018

We present a method we call structure-based preferential bumping,

as a low-cost way to exploit formula structure in VSIDS-based SAT solvers.

We show that the Glucose SAT solver, when modified with preferential bumping

of certain easily identified structurally important variables,

out-performs unmodified Glucose on the industrial formulas

from recent SAT solver competitions.
Termination Casts: A Flexible Approach to Termination with General Recursion
Authors: Stump Aaron , Sjöberg Vilhelm , Weirich Stephanie
Published: January 2018

This paper proposes a type-and-effect system called Teqt, which distinguishes terminating terms and total functions from possibly diverging terms and partial functions, for a lambda calculus with general recursion and equality types. The central idea is to include a primitive type-form ``Terminates t'', expressing that term t is terminating; and then allow terms t to be coerced from possibly diverging to total, using a proof of Terminates t. We call such coercions termination casts, and show how to implement terminating recursion using them. For the meta-theory of the system, we describe a translation from Teqt to a logical theory of termination for general recursive, simply typed functions. Every typing judgment of Teqt is translated to a theorem expressing the appropriate termination property of the computational part of the Teqt term.
The Turing O-Machine and the DIME Network Architecture: Injecting the Architectural Resiliency into Distributed Computing
Authors: Mikkilineni Rao , Comparini Albert , Morana Giovanni
Published: January 2018

Turing’s o-machine discussed in his PhD thesis can perform all of the usual operations of a Turing machine and in addition, when it is in a certain internal state, can also query an oracle for an answer to a specific question that dictates its further evolution. In his thesis, Turing said 'We shall not go any further into the nature of this oracle apart from saying that it cannot be a machine.’ There is a host of literature discussing the role of the oracle in AI, modeling brain, computing, and hyper-computing machines. In this paper, we take a broader view of the oracle machine inspired by the genetic computing model of cellular organisms and the self-organizing fractal theory. We describe a specific software architecture implementation that circumvents the halting and un-decidability problems in a process workflow computation to introduce the architectural resiliency found in cellular organisms into distributed computing machines. A DIME (Distributed Intelligent Computing Element), recently introduced as the building block of the DIME computing model, exploits the concepts from Turing’s oracle machine and extends them to implement a recursive managed distributed computing network, which can be viewed as an interconnected group of such specialized oracle machines, referred to as a DIME network. The DIME network architecture provides the architectural resiliency through auto-failover; auto-scaling; live-migration; and end-to-end transaction security assurance in a distributed system. We demonstrate these characteristics using prototypes without the complexity introduced by hypervisors, virtual machines and other layers of ad-hoc management software in today’s distributed computing environments.
Tutorial on Reasoning in Expressive Non-Classical Logics with Isabelle/HOL
Authors: Steen Alexander , Wisniewski Max , Benzmüller Christoph
Published: January 2018

Non-classical logics (such as modal logics, description logics, conditional logics, multi-valued logics, hybrid logics, etc.) have many applications in artificial intelligence. In this tutorial, we will demonstrate a generic approach to automate propositional and quantified variants of non-classical logics using theorem proving systems for classical higher-order logic. Our particular focus will be on quantified multimodal logics. We will present and discuss a semantical embedding of quantified multimodal logics into classical higher-order logic, which enables the encoding and automated analysis of non-trivial modal logic problems in the Isabelle/HOL proof assistant. Additionally, TPTP compliant automated theorem proving systems can be called from within Isabelle’s Sledgehammer tool for automating reasoning tasks. In the tutorial, we will apply this approach to exemplarily solve a prominent puzzle from the AI literature: the well-known wise men.
Variants of normality and their duals: a pointfree unification of insertion and extension theorems for real-valued functions
Authors: Picado Jorge , Gutiérrez García Javier
Published: January 2018

Several familiar results about normal and extremally disconnected (classical or pointfree) spaces

shape the idea that the two notions are somehow dual to each other and can therefore be studied in

parallel. In this talk we discuss the source of this ‘duality’ and show that each pair of parallel

results can be framed by the ‘same’ proof. The key tools for this purpose are relative notions

of normality, extremal disconnectedness, semicontinuity and continuity (with respect to a fixed

class of complemented sublocales of the given locale) that bring and extend to locale theory a

variety of well-known classical variants of normality and upper and lower semicontinuities in a

illuminating unified manner. This approach allows us to unify under a single localic proof a great variety of

classical insertion results, as well as their corresponding extension results.
On Conflicts and Strategies in QBF
Authors: Bjorner Nikolaj , Janota Mikolas , Klieber William
Published: January 2018

QBF solving techniques can be divided into the DPLL-based and expansion-based.

In this paper we look at how these two techniques can be combined while using strategy extraction as a means

of interaction between the two.

Once propagation derives a conflict for one of the players, we analyse the proof of such and devise a strategy for

the opponent. Subsequently, this strategy is used to constrain the losing player.

The implemented prototype shows feasibility of the approach.

A number of avenues for future research can be envisioned.

Can strategies be employed in a different fashion?

Can better strategy be constructed?

Do the presented techniques generalize beyond QBF?
On the Termination of Positive Supercompilation
Authors: Hamilton Geoff
Published: January 2018

The verification of program transformation systems requires that we prove their termination.

For positive supercompilation, ensuring termination usually requires the memoisation of expressions

which are subsequently used to determine when to perform generalization and folding.

However, determining which expressions to memoise can greatly affect the results obtained.

Memoising too many expressions requires a lot more expensive checking for the possibility

of generalization or folding. More new functions will also be created and generalization will

be performed more often, resulting in less improved residual programs. We would therefore

like to memoise as few expressions as possible, but this could lead to non-termination.

In this paper, we describe a simple pre-processing step which can be applied to programs

prior to transformation by positive supercompilation to ensure that in any potentially infinite

sequence of transformation steps there must be function unfolding. We prove, for programs

that have been pre-processed in this way, that it is only necessary to memoise expressions

immediately before function unfolding to ensure termination, and we demonstrate this on

a number of tricky examples.
My Life with an Automatic Theorem Prover
Authors: Blanchette Jasmin Christian
Published: January 2018

Sledgehammer integrates third-party automatic theorem provers in the proof

assistant Isabelle/HOL. In the seven years since its first release in 2007, it

has grown to become an essential part of most Isabelle users' workflow. Although

a lot of work has gone into tuning the system, the main reason for

Sledgehammer's success is the impressive power of the external provers,

especially E, SPASS, Vampire, and Z3. In this paper, I review

Vampire's strengths and weaknesses in this context and propose a few

directions for future work.
A Smart Grid Energy Management Problem for Data-driven Design with Probabilistic Reachability Guarantees
Authors: Ioli Daniele , Falsone Alessandro , Hartung Marianne , Busboom Axel , Prandini Maria
Published: January 2018

In this paper we describe an energy management benchmark problem for a smart grid where electrical energy is supplied to a load via local power production from a solar PhotoVoltaic (PV) installation. The smart grid is connected with the main grid, which can eventually provide the energy needed for balancing demand and generation. The goal is to set the battery energy flow so as to keep the energy exchange with the main grid as close as possible to a nominal profile, within certified bounds, avoiding the fluctuations caused by the local PV energy production. Some energy production profiles of the PV installation and environmental data on irradiation and temperature are available for the design of the energy management strategy, together with a hybrid model for the battery and the electrical load profile. We describe a data-driven solution, pointing out its limits and providing some hint on possible direction for improvement.
Refinement and Term Synthesis in Loop Invariant Generation
Authors: Maclean Ewen , Ireland Andrew , Dixon Lucas , Atkey Robert
Published: January 2018

We present a technique for refining incorrect or insufficiently strong loop invariants in correctness proofs for imperative programs. We rely on previous work [16] in combining program analysis and Proof Planning, and exploit IsaPlanner’s use of meta-variables and goal-naming to generate correct loop invariants. We present a simple example in detail and show how this scales to more complex problems.
Non-linear Second Order Abstract Categorial Grammars and Deletion
Authors: Salvati Sylvain
Published: January 2018

We prove that non-linear second order Abstract Categorial Grammars

(2ACGs) are equivalent to non-deleting 2ACGs. We prove this result

first by using the intersection types discipline. Then we explain

how coherence spaces can yield the same result. This result shows

that restricting the Montagovian approach to natural language

semantics to use only $\L I$-terms has no impact in terms of the

definable syntax/semantics relations.
Model checking Timed CSP
Authors: Armstrong Philip , Lowe Gavin , Ouaknine Joël , Roscoe Bill
Published: January 2018

Though Timed CSP was developed 25 years ago and the CSP-based

refinement checker FDR was first released 20 years ago, there has never been

a version of this tool for Timed CSP. In this paper we report on the creation of

such a version, based on the digitisation results of Ouaknine} and

the associated development of discrete-time versions of Timed CSP with

associated models.
Effect algebras, witness pairs and observables
Authors: Jenča Gejza
Published: January 2018

The category of effect algebras is the Eilenberg-Moore category for the

monad arising from the free-forgetful adjunction between categories of bounded posets

and orthomodular posets.

In the category of effect algebras, an observable is a morphism whose domain

is a Boolean algebra. The characterization of subsets of ranges of observables is

an open problem.

For an interval effect algebra E, a witness pair for a subset of S is an object

living within E that "witnesses existence" of an observable whose range

includes S. We prove that there is an adjunction between the poset of all

witness pairs of E and the category of all partially inverted E-valued

observables.
Generalisation of Induction Formulae based on Proving by Symbolic Execution
Authors: Wallenburg Angela
Published: January 2018

Induction is a powerful method that can be used to prove the total correctness of program loops. Unfortunately the induction proving process in an interactive theorem prover is often very cumbersome. In particular it can be difficult to find the right induction formula. We describe a method for generalising induction formulae by analysing a symbolic proof attempt in a semi-interactive first-order theorem prover. Based on the proof attempt we introduce universally quantified variables, meta-variables and sets of constraints on these. The constraints describe the conditions for a successful proof. By the help of examples, we outline some classes of problems and their associated constraint solutions, and possible ways to automate the constraint solving.
Is it possible to unify sequential programs?
Authors: Novikova Tatyana , Zakharov Vladimir
Published: January 2018

We introduce a first-order model of imperative sequential programs and set up formally the unification problem in this model: given a pair of programs π1 and π2 find a pair of substitutions (θ1,θ2) such that the instances π1θ1 and π2θ2 of these programs are equivalent, i.e. compute the same function. Since functional equivalence of programs is undecidable, we choose its decidable approximation --- a strong equivalence, --- which is well-known in theory of program schemata. Our main result is a polynomial time unification algorithm for sequential programs w.r.t. strong equivalence of programs.
Spectra of finitely presented lattice-ordered Abelian groups and MV-algebras, part 1
Authors: Marra Vincenzo , McNeill Daniel , Pedrini Andrea
Published: January 2018

This is the first part of a series of two abstract, the second one being by Daniel McNeill.

If X is any topological space, its collection of opens sets O(X) is a complete distributive lattice and also a Heyting algebra. When X is equipped with a distinguished basis D(X) for its topology, closed under finite meets and joins, one can investigate situations where D(X) is also a Heyting subalgebra of O(X).

Recall that X is a spectral space if it is compact and T0, its collection D(X) of compact open subsets forms a basis which is closed under finite intersections and unions, and X is sober. By Stone duality, spectral spaces are precisely the spaces arising as sets of prime ideals of some distributive lattice, topologised with the Stone or hull-kernel topology. Specifically, given such a spectral space X, its collection of compact open sets D(X) is (naturally isomorphic to) the distributive lattice dual to X under Stone duality.

We are going to exhibit a significant class of such spaces for which D(X) is a Heyting subalgebra of O(X).

We work with lattice-ordered Abelian groups and vector spaces. Using Mundici’s Gamma-functor the results can be rephrased in terms of MV-algebras, the algebraic semantics of Lukasiewicz infinite-valued propositional logic.

Let (G,u) be a finitely presented vector lattice (or Q-vector lattice, or l-group) G equipped with a distinguished strong order unit u. It turns out that Spec(G,u), i.e. the the space of prime ideals of (G,u) topologised with the hull-kernel topology, is a compact spectral space. Our first main result states that the collection D(Spec(G,u)) of compact open subsets of Spec(G,u) is a Heyting subalgebra of the Heyting algebra of open subsets O(Spec(G,u)).

As a consequence, we also prove that the subspace Min(G,u) of minimal prime ideals of G is a Boolean space, i.e. a compact Hausdorff space whose clopen sets form a basis for the topology.

Further, for any fixed maximal ideal m of G, the set l(m) of prime ideals of G contained in m, equipped with the subspace topology, is a spectral space, and the subspace Min(l(m)) of l(m) is a Boolean space.
Constraint Problem Specification as Compression
Authors: Prestwich Steve , Tarim S. Armagan , Rossi Roberto
Published: January 2018

Constraint Programming is a powerful and expressive framework for modelling and solving combinatorial problems. It is nevertheless not always easy to use, which has led to the development of high-level specification languages. We show that Constraint Logic Programming can be used as a meta-language to describe itself more compactly at a higher level of abstraction. This can produce problem descriptions of comparable size to those in existing specification languages, via techniques similar to those used in data compression. An advantage over existing specification languages is that, for a problem whose specification requires the solution of an auxiliary problem, a single specification can unify the two problems. Moreover, using a symbolic representation of domain values leads to a natural way of modelling channelling constraints.
Benchmark Problem: A PK/PD Model and Safety Constraints for Anesthesia Delivery
Authors: Gan Victor , Dumont Guy , Mitchell Ian
Published: January 2018

Hypnosis, or depth of unconsciousness, is one of the goals of general anesthesia. In this brief paper we provide a differential equation model of how propofol, a commonly used intravenous anesthetic drug, leads to hypnosis. The model has two components: the pharmacokinetics (PK) describing how the drug is metabolized by the body, and the pharmacodynamics (PD) describing how the drug effects the depth of hypnosis. This standard PK/PD model is a compartmental model, and is linear except for an internal time delay and a nonlinear output mapping. We discuss how this model can be simplified and/or complexified so as to take best advantage of the capabilities of a particular analysis method. One goal of developing such a model is to ensure patient safety during surgery, so we describe an example safety verification problem. Finally, in order to demonstrate that this benchmark is operational, we provide code to simulate one version of the system.
Jankov Formula and Ternary Deductive Term
Authors: Citkin Alex
Published: January 2018

Grounding on defining relations of a finitely presentable subdirectly irreducible (s.i.) algebra in a variety with a ternary deductive term (TD), we define the characteristic identity of this algebra. For finite s.i. algebras the characteristic identity is equivalent to the identity obtained from Jankov formula. In contrast to Jankov formula, characteristic identity is relative to a variety and even in the varieties of Heyting algebras there are the characteristic identities not related to Jankov formula. Every subvariety of a given locally finite variety with a TD term admits an optimal axiomatization consisting of characteristic identities. There is an algorithm that reduces any finite system of axioms of such a variety to an optimal one. Each variety with a TD term can be axiomatized by characteristic identities of partial algebras, and in certain cases these identities are related to the canonical formulas.
A Framework for Verified Depth-First Algorithms
Authors: Neumann René
Published: January 2018

We present a framework in Isabelle/HOL for formalizing variants of

depth-first search. This framework allows to easily prove non-trivial

properties of these variants. Moreover, verified code in several

programming languages including Haskell, Scala and Standard ML can be

generated.

In this paper, we present an abstract formalization of depth-first search and

demonstrate how it is refined to an efficiently executable version. Further we use the emptiness-problem of Büchi-automata known from model checking as the motivation to present three Nested DFS algorithms. They are formalized, verified and transformed into executable code using our framework.
Chang-Mundici construction of an enveloping unital lattice-group of a BL-algebra
Authors: Lele Celestin , Nganou Jean Bernard
Published: January 2018

For any BL-algebra L, we construct an associated lattice ordered Abelian group that coincides with the Chang’s l-group of an MV-algebra when the BL-algebra is an MV-algebra. We prove that the Chang’s group of the MV-center of any BL-algebra L is a direct summand in the above group. We also find a direct description of the complement of the Chang’s group of the MV-center in terms of the filter of dense elements of L. Finally, we compute some examples of the introduced group.
A Prolog-based Proof Tool for Type-Theory TA-lambda and Implicational Intuitionistic-Logic
Authors: Stefanus L. Yohanes , Santoso Ario
Published: January 2018

Studies on type theory have brought numerous important contributions to computer science. In this paper we present a GUI-based proof tool that provides assistance in constructing deductions in type theory and validating implicational intuitionistic logic formulas. As such, this proof tool is a testbed for learning type theory and implicational intuitionistic logic. This proof tool focuses on an important variant of type theory named TAλ, especially on its two core algorithms: the principal-type algorithm and the type inhabitant search algorithm. The former algorithm finds a most general type assignable to a given λ-term, while the latter finds inhabitants (closed λ-terms in β-normal form) to which a given type can be assigned. By the Curry-Howard correspondence, the latter algorithm provides provability for implicational formulas in intuitionistic logic. We elaborate on how to implement those two algorithms declaratively in Prolog and the overall GUI-based program architecture. In our implementation, we make some modification to improve the performance of the principal-type algorithm. We have also built a web-based version of the proof tool called λ-Guru.
Beagle as a HOL4 external ATP method
Authors: Gauthier Thibault , Kaliszyk Cezary , Keller Chantal , Norrish Michael
Published: January 2018

This paper presents BEAGLE TAC, a HOL4 tactic for using Beagle as an external ATP for

discharging HOL4 goals. We implement a translation of the higher-order goals to the TFA

format of TPTP and add trace output to Beagle to reconstruct the intermediate steps derived

by the ATP in HOL4. Our translation combines the characteristics of existing successful

translations from HOL to FOL and SMT-LIB, however we needed to adapt certain stages

of the translation in order to benefit form the expressivity of the TFA format and the power

of Beagle. In our initial experiments, we demonstrate that our system can prove, without

any arithmetic lemmas, 81% of the goals solved by Metis.
Tool Presentation: Isabelle/HOL for Reachability Analysis of Continuous Systems
Authors: Immler Fabian
Published: January 2018

We present a tool for reachability analysis of continuous systems based on

affine arithmetic and Runge-Kutta methods. The distinctive feature of our tool

is its verification in the interactive theorem prover Isabelle/HOL: the

algorithm is guaranteed to compute safe overapproximations, taking into account

all round-off and discretization errors.
Computer algebra investigation of known primitive triangle-free strongly regular graphs
Authors: Ziv-Av Matan , Klin Mikhail
Published: January 2018

With the aid of computer algebra systems COCO and GAP with

its packages we are investigating all seven known primitive

triangle-free strongly regular graphs on 5, 10, 16, 50, 56,

77 and 100 vertices. These graphs are rank 3 graphs, having

a rich automorphism group. The embeddings of each graph

from this family to other ones are described, the

automorphic equitable partitions are classified, all

equitable partitions in the graphs on up to 50 vertices are

enumerated. Basing on the reported computer aided results

and using techniques of coherent configurations, a few new

models of these graphs are suggested, which are relying on

knowledge of just a small part of symmetries of a graph in

consideration.
An analogue of Bull's theorem for Hybrid Logic
Authors: Robinson Claudette , Conradie Willem
Published: January 2018

Hybrid logic extends modal logic with a special sort of variables, called nominals, which are evaluated to singletons in Kripke models by valuations, thus acting as names for states in models. Various syntactic mechanisms for exploiting and enhancing the expressive power gained through the addition of nominals can be included, most characteristically the satisfaction operator, @_ip, allowing one to express that p holds at the world named by a nominal i.

R.A. Bull famously proved that each normal extension of S4.3 has the finite model

property. In the current paper, we prove a hybrid analogue of Bull's result. Like the proof of Bull's original result, ours is algebraic, and thus our secondary aim with this work is to illustrate the usefulness of algebraic methods within hybrid logic research, a field where such methods have been largely ignored.
Statistical Methodology for Comparison of SAT Solvers
Authors: Nikolić Mladen
Published: January 2018

Evaluating improvements to modern SAT solvers and comparison of two arbitrary solvers is a challenging and important task. Relative performance of two solvers is usually assessed by running them on a set of SAT instances and comparing the number of solved instances and their running time in a straightforward manner. In this paper we point to shortcomings of this approach and advocate more reliable, statistically founded methodologies that could discriminate better between good and bad ideas. We present one such methodology and illustrate its application.
Lattice model refinement of protein structures
Authors: Mann Martin , Dal Palù Alessandro
Published: January 2018

To find the best lattice model representation of a given full atom protein structure is a hard computational problem. Several greedy methods have been suggested where results are usually biased and leave room for improvement. In this paper we formulate and implement a Constraint Programming method to refine such lattice structure models. We show that the approach is able to provide better quality solutions. The prototype is implemented in COLA and is based on limited discrepancy search. Finally, some promising extensions based on local search are discussed.
Complexity of Admissible Rules in the Implication-Negation Fragment of Intuitionistic Logic
Authors: Cintula Petr , Metcalfe George
Published: January 2018

The goal of this paper is to study the complexity of the set of admissible rules of the implication-negation fragment of intuitionistic logic IPC. Surprisingly perhaps, although this set strictly contains the set of derivable rules (the fragment is not structurally complete), it is also PSPACE-complete. This differs from the situation in the full logic IPC where the admissible rules form a co-NEXP-complete set.
Benchmark: Reachability on a model with holes
Authors: Heinz Thomas , Oehlerking Jens , Woehrle Matthias
Published: January 2018

The benchmark presented in this paper is an example for verification of a hybrid system model with so-called holes, i.e. part of the system behaviour is not specified. Verification of such a model allows 3rd parties to plug a specific behaviour into a hole without changing desirable properties of the system. The particular example is based on an open-source robotics application, namely a self-balancing two-wheeled robot which is essentially modeled as an inverted pendulum. The balance controller provides two input signals for translational (forward/backward) and rotational (left/right turn) motion which can be driven by arbitrary path planning applications. Examples for such applications are line following and pursuit-evasion algorithms as well as a remote control which allows trajectories to be defined externally. These motion trajectories may or may not yield a state from which the balance controller is unable to recover, which means that the robot falls over. Hence, the verification goal is to prove the safety property that the body pitch angle is bounded under motion trajectories.
Formal Replay of Translation Validation for Highly Optimised C
Authors: Sewell Thomas
Published: January 2018

In previous work [Sewell, Myreen and Klein, 2013] we have implemented a

translation validation mechanism for checking that a C compiler is adhering

to the expected semantics of a verified program. We used this apparatus to

check the compilation of the seL4 verified operating system

kernel [Klein et.al. 2009] by GCC 4.5.1. To get this result, we

carefully chose a problem representation that worked well with certain highly

optimised SMT solvers. This raises a question of correctness. While we are

confident the result is correct, we still aim to replay this result with the

most dependable tools available.

In this work we present a formalisation of the proof rules needed to replay

the translation check within the theorem prover Isabelle/HOL. This is part of

an ongoing effort to bring the entire translation validation result within a

single trusted proof engine and derive a single correctness theorem, thus

reaching the gold standard level of trustworthiness for program verification.

We had hoped to present the formal rule set in action through a worked example.

Unfortunately while we have all the theory we need, the mechanisms for

selecting and applying the rules and discharging certain side conditions remain

a work in progress, and our example proof is incomplete.
Boolean like algebras
Authors: Ledda Antonio , Kowalski Tomasz , Paoli Francesco , Salibra Antonino
Published: January 2018

Using Vaggione's concept of central element in a double pointed algebra, we

introduce the notion of Boolean like variety as a generalisation of

Boolean algebras to an arbitrary similarity type. Appropriately relaxing the

requirement that every element be central in any member of the variety, we

obtain the more general class of semi-Boolean like varieties, which

still retain many of the pleasing properties of Boolean algebras. We prove

that a double pointed variety is discriminator iff it is semi-Boolean like,

idempotent, and 0-regular. This theorem yields a new Maltsev-style

characterisation of double pointed discriminator varieties.

Moreover, we point out the exact relationship between semi-Boolean-like

varieties and the quasi-discriminator varieties, and we provide

semi-Boolean-like algebras with an explicit weak Boolean product

representation with directly indecomposable factors. Finally, we discuss idempotent

semi-Boolean-like algebras. We consider a noncommutative generalisation of Boolean algebras and prove - along the lines of similar results available for pointed discriminator varieties or for varieties with a commutative ternary deduction term that every idempotent semi-Boolean-like variety is term equivalent to a variety of noncommutative Boolean algebras with additional operations.