bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorus fertilisation under nitrogen limitation can deplete soil carbon stocks: evidence from Swedish meta-replicated long-term field experiments
Authors: Poeplau Christopher , Bolinder Martin A. , Kirchmann Holger , Kätterer Thomas
Published: February 2016

Abstract. Increasing soil organic carbon (SOC) in agricultural soils can mitigate atmospheric CO2 concentration and also contribute to increased soil fertility and ecosystem resilience. The role of major nutrients in SOC dynamics is complex, due to simultaneous effects on net primary productivity (NPP) that influence crop residue carbon inputs and in the rate of heterotrophic respiration (carbon outputs). This study investigated the effect on SOC stocks of three different levels of phosphorus and potassium (PK) fertilisation rates in the absence of nitrogen fertilisation and of three different levels of nitrogen fertiliser in the absence of PK fertiliser. This was done by analysing data from 10 meta-replicated Swedish long-term field experiments (> 45 years). With N fertilisation, SOC stocks followed yield increases. However, for all PK levels, we found average SOC losses ranging from −0.04 ± 0.09 Mg ha−1 yr−1 (ns) for the lowest to −0.09 ± 0.07 Mg ha−1 yr−1 (p =  0.008) for the highest application rate, while crop yields as a proxy for carbon input increased significantly with PK fertilisation by 1, 10 and 15 %. We conclude that SOC dynamics are mainly output-driven in the PK-fertilised regime but mostly input-driven in the N-fertilised regime, due to the much more pronounced response of NPP to N than to PK fertilisation. It has been established that P rather than K is the element affecting ecosystem carbon fluxes, where P fertilisation has been shown to (i) stimulate heterotrophic respiration, (ii) reduce the abundance of arbuscular mycorrhizal fungi and (iii) decrease the crop root : shoot ratio, leading to higher root-derived carbon input. The higher export of N in the PK-fertilised plots in this study could (iv) have led to increased N mining and thus mineralisation of organic matter. More integrated experiments are needed to gain a better understanding of the relative importance of each of the above-mentioned mechanisms leading to SOC losses after P addition.
Examining the fixation kinetics of chelated and non-chelated copper and the applications to micronutrient management in semiarid alkaline soils
Authors: Udeigwe T. K. , Eichmann M. B. , Menkiti M. C. , Kusi N. Y. O.
Published: February 2016

Abstract. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semiarid soils of the Southern High Plains, USA, using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system compared to the chelated within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrients over time, highlighting the significance of timing even when chelated micronutrients are used. The strengths of the relationship of change in available Cu with respect to other micronutrients (iron (Fe), manganese (Mn), and zinc (Zn)) were higher in the non-chelated system (R2: 0.68–0.94), compared to the chelated (R2: 0.42–0.81), with slopes of 0.40 (Cu–Fe), 0.31 (Cu–Mn), and 1.04 (Cu–Zn) in the non-chelated system and 0.26 (Cu–Fe), 0.22 (Cu–Mn), and 0.90 (Cu–Zn) in the chelated system. Reduction in the amount of available Cu was best described by the power function model (R2 =  0.91, SE  =  0.081) in the non-chelated system and second-order model (R2 =  0.95, SE  =  0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semiarid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.
Educational and Ethical Views of Attar Neishabouri
Authors: Yazdani Reza
Published: February 2016

Attar believes that some health standards and different hygienic methods should be taught to children. Although teaching the methods of healthcare and well-being is among the necessities of life, child’s understanding and intelligence should not be ignored. There is no doubt that religious give great importance to health issues and even emphasize that they should be taught to children. Dealing with appearance causes that their truth-seeking spirit is misled. Accordingly, Sufism recommends people to abandon appearance and deal with the interior. In the stages of growth, child’s mental images are related to sensory issues. He gradually understands lighting, heating and other things that are exposed to his senses and realizes their differences. Formation of mental images and attention to their differences are related to the growth and complexity of the child’s nerves and experience. Affection and kindness to children is desirable. But parents and educators should know that going to extremes in this case is harmful. Attar believes that loving the children excessively causes that he is brought up as a weak and powerless person and loses his self-confidence. So, he shows weakness in the face of problems. But if he is educated with moderation, he will act accordingly. Too much attention to children makes them timid. Treating the children with justice and fairness is one of the Divine attributes. According to Attar, parents should not discriminate between their children and should deal with them justly in all aspects just as you like to be treated with justice in all situations. In many educational books, it is said that the apparent treatment of parents with children may vary according to their age and gender and this is difference rather than discrimination. Attar states that we should act carefully and accurately. These differences should not make parents not act fairly in loving children, but they should justify the children that if they were in such a situation, they would receive the same treatment. Discrimination and injustice in the family, whether tangible or intangible, cause that children feel contempt and become alienated from their family and education.
Surface Behavior and Thickness Measurement of Free Standing Thin Film of Liquid Crystal Compound Biphenyl (E7)
Authors: Asif Siddiqui  , Zaheer Uddin  , S. Naseem Shah
Published: February 2016

A simple experimental setup based on a polarizing optical technique is designed to find the thickness of free standing thin film of Biphenyl (E7). Monochromatic light is passed through a liquid crystal thin film in two different modes of placement. In each mode approximately 10 mg of Biphenyl is used. The films of varying area were used in this study. The thin films were highly stable and could survive more than one day. The intensity of transmitted monochromatic radiation is measured using this technique by placing thin film in horizontal and vertical modes. Using Beer-Lambert’s Law the thickness of thin film is also measured using polarizing optical technique. In both the modes (horizontal and vertical) different behaviors of thickness of thin film are observed..
Physical and Chemical Mutation for Enhanced Alpha-Amylase Production by Aspergillus fumigatus NTCC1222 under Solid State Fermentation Conditions Using Agri-Residue Waste
Authors: Shalini Singh  , Sanamdeep Singh  , Jyoti Mangla
Published: February 2016

The search for better microbial sources of enzymes has long been an area of active research owing to the clear and distinct importance in todays’ world where exploration and application of environment friendly products has become a necessity. Though the natural, wild microbial strains, are continuously be searched and explored for their potential for amylase production yet, simultaneous attempts for improved enzyme production are necessary too. In the present study, a comparison between the influence of different mutational treatments (UV treatment and EMS-EtBr treatment) on amylase production was studied. Aspergillus fumigatus NTCC1222, an indigenously isolated amylase producer, which has shown an amylase activity of 341.7 U/mL under optimized conditions of SSF in our previous study, was subjected to UV- and EMS-EtBr- treatment for possible improved amylase production under optimized solid state fermentation conditions. The UV mutated strains yielded an amylase production of 614.2 U/mL while the chemically (EMS-EtBr) mutated strain produced 814.1 U/mL of amylase activity thereby indicating the successful enhancement in amylase activity for the test fungal strain.
Drug Release Profile and Cellular Uptake of Polymeric Prodrugs Synthesized from Amphiphilic Blockcopolymer Using Mechanically Produced Macromonomers Possessing Anhydrate as a Terminal Group
Authors: Shin-ichi  Kondo  , Sayaka  Kimura  , Kenjiro  Tatematsu  , Yuka  Sawama  , Naoki  Doi  , Yasushi Sasai  , Yukinori Yamauchi  , Masayuki Kuzuya
Published: February 2016

In this paper, the polymeric micelle was fabricated with amphiphilic block copolymer which was synthesized by the condensation of mechanochemically produced PBzMA macromonomer with a-methyl-w-aminopropoxy polyoxyethylene. Although the polymeric micelles containing 5-fluorouracil (5-FU) or rohdamine showed the narrow size distribution as well as blank polymeric micelles, the particle diameter of the polymeric micelles containing 5-FU or rohdamine was larger than that of blank polymeric micelle. Polymeric micelle containing 5-FU slowly released 5-FU and about 10 % of 5-FU was released within 72 h. The present polymeric micelle was uptaken by A549 cells, but HepG2 cells did not. Cytotoxicity of Polymeric micelle containing 5-FU was not observed against HepG2 and A549 cells in this experimental condition. It was considered that the slow release of 5-FU from Polymeric micelle might cause the insufficient cytotoxicity.
On Minimum Weight Binary Representation of Integers and Continued Fractions with Application to Computer Arithmetic
Authors: Matula David W. , Kornerup Peter
Published: February 2016

We develop the concept of minimum weight binary continued fraction representation of a rational number as an extension of minimum weight binary radix representation of an integer. The relation of these representations to the attainment of optimum efficiency in the shift and add or subtract model of binary computer arithmetic is discussed.
An Integrated Rational Arithmetic Unit
Authors: Matula David W. , Kornerup Peter
Published: February 2016

Based on the classical Euclidian Algorithm, we develop the foundations of an arithmetic unit performing Add, Subtract, Multiply and Divide on rational operands. The unit uses one unified algorithm for all operations, including rounding. A binary implementation, based on techniques known from the SRT division, is described. Finally, a hardware implementation using ripple-free, carry-save addition is analyzed, and adapted to a floating-slash representation of the rational operands.
A Denotational Framework for Data Flow Analysis
Authors: Nielson Flemming
Published: February 2016

It is shown how to express data flow analysis in a denotational framework by means of abstract interpretation. A continuation style formulation naturally leads to the MOP (Meet Over all Paths) solution, whereas a direct formulation leads to the MFP (Maximal Fixed Point) solution.
A Programming Language for the Inductive Sets, and Applications
Authors: Harel David , Kozen Dexter
Published: February 2016

We introduce a programming language IND that generalizes alternating Turing machines to arbitrary first-order structures. We show that IND programs (respectively, everywhere-halting IND programs, loop-free IND programs) accept precisely the inductively definable (respectively, hyperelementary, elementary) relations. We give several examples showing how the language provides a robust and computational approach to the theory of first-order inductive definability. We then show: (1) on all acceptable structures (in the sense of Moschovakis), r.e. Dynamic Logic is more expressive than finite-test Dynamic Logic. This refines a separation result of Meyer and Parikh; (2) IND provides a natural query language for the set of fixpoint queries over a relational database, answering a question of Chandra and Harel.
Formal Semantics by a Combination of Denotational Semantics and High-Level Petri Nets
Authors: Hansen Niels Damgaard , Madsen Kim Halskov
Published: February 2016

Denotational semantics has proved to be an excellent tool for the specification of nearly all kinds of declarations and commands in sequential languages, but the description of concurrent processes is in practice nearly impossible.

High-level Petri nets, on the other hand, have proved their value in the specification of communication and synchronization of concurrent processes.

We propose to combine the two models into a single approach, where denotational semantics is used to build up environments and to describe store transformations, while Petri nets are used to describe sequencing and communication.
Syntax Directed Program Modularization
Authors: Kristensen Bent Bruun , Madsen Ole Lehrmann , Møller-Pedersen Birger , Nygaard Kristen
Published: February 2016

The intent of this paper is to illustrate the following general ideas:

-- Use of the context free grammar of a programming language as an integrated part of its programming system.

-- Reconsideration of the border line between language and system.

-- Systematic modularization of programs for the various translation phases.

The specific ideas presented in this paper are language independent methods for handling:

-- Modularization of programs.

-- Separate translation in the form of context sensitive parsing (type checking) of modules.

-- Protection of part of a module, e.g. protection of the representation of an abstract data type.

The mechanism for modularization is unusual as it is based on the context-free syntax of the language. A module may be a sentential form generated by any nonterminal of the grammar.
PAL - A Language for Multiple-Precision Algorithms
Authors: Hagerup Torben
Published: February 2016

Traditional notations (programming languages) are seldom adequate for the description of multiple-precision computations. This is because there is no way to specify how accurately the arithmetic operations should be carried out.

This paper presents a special-purpose programming language which allows multiple-precision algorithms to be stated accurately and elegantly.
Design Issues for a Dexter-based Hypermedia System
Authors: Grønbæk Kaj , Trigg Randall H.
Published: February 2016

This paper discusses experiences and lessons learned from the design of an open hypermedia system, one that integrates applications and data not ''owned'' by the hypermedia. The Dexter Hypertext Reference Model was used as the basis for the design. Though our experiences were generally positive, we found the model constraining in certain ways and underdeveloped in others. For instance, Dexter argues against dangling links, but we found several situations where permitting and supporting dangling links was advisable. In Dexter, the data objects making up a component's contents are encapsulated in the component; in practice, references to objects stored apart from the hyper media structure should be allowed. We elaborate Dexter's notion of composite component to include composites that ''contain'' other components and composites with structured contents, among others. The paper also includes a critique of Dexter's notion of link directionality, proposes a distinction between marked and unmarked anchors, and discusses anchoring within a composite.
Metoder til teknologivurdering: - overvejelser over praksis i Utopia-projektet
Authors: Bødker Susanne
Published: February 2016

I Utopia-projektet, som er et nordisk fagligt forskningsprojekt, samarbejder grafiske arbejdere, dataloger og samfundsvidenskabsfolk om at udvikle alternativ teknologi til tekst- og billedbehandling i den grafiske branche. Som en del af denne udvikling gennemføres teknologivurdering under forskellige former.

Artiklen er disponeret som følger: først gives en kort præsentation af Utopia-projektets formål og forløb, dernæst karakteriseres Utopia som teknologivurderingsprojekt, og de metoder, som anvendes i Utopia, præsenteres. På baggrund af erfaringerne fra Utopia gives altså konkrete forslag til metoder til teknologivurdering, hvorefter der konkluderes.
Towards Reachability Trees for High-level Petri Nets
Authors: Huber Peter , Jensen Arne M. , Jepsen Leif Obel , Jensen Kurt
Published: February 2016

High-level Petri nets have been introduced as a powerful net type, by which it is possible to handle rather complex systems in a succinct and manageable way. The success of high-level Petri nets is undebatable when we speak about description, but there is still much work to be done to establish the necessary analysis methods. It has already been shown how to generalize the concept of place-invariants and transition-invariants, from place-transition-nets to high-level Petri nets. Our present paper constitutes the first steps towards a generalization of reachability trees, which is one of the other important analysis methods known for PT-nets.

The central idea in our paper is the observation, that HL-nets often possess classes of equivalent markings. As an example an HL-net describing the five dining philo\-sophers has an equivalence-class consisting of those five markings in which exactly one philosopher is eating. These five markings are interchangeable, in the sense that their subtrees represent equivalent behaviours, where the only difference is the identity of the involved philosophers and forks. If we analyze one of these subtrees, we also understand the behaviour of the others.

We describe an algorithm which constructs the HL-tree. The algorithm can easily be automated and we will soon start the work on an implementation. The constructed HL-trees turn out to be considerably smaller than the corresponding PT-trees (reachability trees for the equivalent PT-nets).
Mapping Situations within a System Development Project.: An Intervention Perspective on Organizational Change
Authors: Lanzara Giovan Francesco , Mathiassen Lars
Published: February 2016

In this paper we propose some new tools for mapping system development projects. Maps -- as we propose them -- contain descriptions and interpretations of project situations:they are helpful in collecting and organizing relevant, often neglected knowledge and experience.

Maps are cognitive constructs containing pictures that actors make of the situation in which they are involved. They are typically made within the situation or transposed from similar situations and are used by the actors themselves as tools for exploring, for learning, for increasing awareness, for inventing solutions to problems, and for undertaking action.
Systems Development: Possibilities for and Obstacles to Changing Practice
Authors: Kensing Finn
Published: February 2016

Too little time, too few people, and too poor techniques and tools are frequent explanations of why a system development project does not come up to expectations. This article will discuss some other explanations centering around two concepts: approaching the product and handling project situations. The article is partly inspired by Schön's studies of how various professionals think when they work, and partly by my own studies of the working practices of computer specialists.
Learnability
Authors: Frandsen Gudmund Skovbjerg
Published: February 2016

Les Valiant has recently conceived a remarkable mathematical model of learnability. The originality appears through several facets of the model. Objects belonging to a specific concept are given a measure of naturalness in the form of a probability distribution. The learning of a concept takes place by means of a protocol that among other tools allows the use of a source of natural examples. A concept is learnable if a recognition algorithm can be synthesized within a polynomial number of steps. The recognition algorithm is allowed to be incorrect for an adjustable fraction of inputs measured with respect to naturalness.

Technically the model is based on the propositional logic over a finite number of Boolean variables. However, the underlying ideas are quite universal and can be realised by means of an almost arbitrary formal language, which we will demonstrate in this note. A single concept may include infinitely many objects within a formal language frame. Fortunately we can learn such concepts from finite sets of examples only. We shall prove a specific class of concepts to be learnable within the nontrivial formal language of predicate logic.
Problem-heap: A Paradigm for Multiprocessor Algorithms
Authors: Møller-Nielsen Peter , Staunstrup Jørgen
Published: February 2016

The problem-heap paradigm has evolved through four years of experiments with the Multi-Maren multiprocessor. Problem-heap algorithms have been formulated for a number of different tasks such as numerical problems, sorting, searching and optimization. Although these tasks are very different, the analyses of the running times of all the problem-heap algorithms are very similar. The problem-heap paradigm is illustrated by algorithms which have been implemented and analyzed using the Multi-Maren multiprocessor.
A Denotational Semantics for Logic Programming
Authors: Frandsen Gudmund Skovbjerg
Published: February 2016

A fully abstract denotational semantics for logic programming has not been constructed yet. In this paper we present a denotational semantics that is almost fully abstract. We take the meaning of a logic program to be an element in a Plotkin power domain of substitutions. In this way our result shows that standard domain constructions suffice, when giving a semantics for logic programming. Using the well-known fixpoint semantics of logic programming we have to consider two different fixpoints in order to obtain information about both successful and failed computations. In contrast, our semantics is uniform in that the (single) meaning of a logic program contains information about both successful, failed and infinite computations. Finally, based on the full abstractness result, we argue that the detail level of substitutions is needed in any denotational semantics for logic programming.
The Potential Use of Action Semantics in Standards
Authors: Mosses Peter D. , Watt David A.
Published: February 2016

Current standards for programming languages generally use informal, rather than formal, semantic descriptions. Possible reasons for this are discussed. Action Semantics, which has been developed from Denotational Semantics and Abstract Semantic Algebras, has some features that may make it more attractive for use in standards than other formal approaches. This paper describes and motivates Action Semantics, and gives some realistic examples of its use.
Inheritance Used to Factorize: Distributed Termination Detection Algorithms
Authors: Thomsen Kristine Stougård
Published: February 2016

A multiple inheritance mechanism on processes is introduced. Processes are described in classes, and the different action parts of a process inherited from different classes are executed in a coroutine-like style called alternation.

The inheritance mechanism is a useful tool for factorizing the description of common aspects of processes. This is demonstrated within the domain of distributed programming by using the inheritance mechanism to factorize the description of distributed termination detection algorithms from the description of the distributed main computations for which termination is to be detected.

The factorization is obtained by programming the termination detection algorithms in separate classes. The main computations are programmed in classes that use appropriate termination detection classes as superclasses. A clear separation of concerns is obtained, and arbitrary combinations of termination detection algorithms and main computations can be formed.
Viden om systemudvikling
Authors: Munk-Madsen Andreas
Published: February 2016

Denne artikel behandler udvalgte videnskabsteoretiske spørgsmål i forbindelse med systemudvikling. Artiklen diskuterer skriftlig repræsentation af viden, udvikling af viden og praktisk anvendelse af viden om systemudvikling.
Project Evaluation - Setting the Problem
Authors: Munk-Madsen Andreas
Published: February 2016

Evaluation of a system development project denotes those activities which aim at improving the understanding of the project and its environment. This understanding forms the basis for planning and regulating the course of the project. Project evaluation often takes place in a project situation which only deviates slightly from the plan. The project is then evaluated merely to determine the extent and consequences of the deviations. There are situations however, where the system developers know that something is wrong in the project. But maybe they cannot identify the problem, or they disagree on what the problem is. The task is to set the problem. This paper discusses how project evaluation can be performed in situations like that. It discusses guidelines for defining problems, and claims that a problem should be formulated as a contradiction. Project graphs and problem networks are introduced as description tools in project planning and project evaluation, respectively.
The Use of Action Semantics
Authors: Mosses Peter D. , Watt David A.
Published: February 2016

Formal descriptions of semantics have so far failed to match the acceptance and popularity of formal descriptions of syntax. Thus, in current standards for programming languages, syntax is usually described formally but semantics informally, despite the greater danger of impreciseness in the description of semantics. Possible reasons for this state of affairs are discussed. Action Semantics, which has been developed from Denotational Semantics and Abstract Semantic Algebras, has some features that may make it more attractive than other semantic formalisms. This paper describes and motivates Action Semantics, and gives some realistic examples of its use.
A Modal Logic for a Subclass of Event Structures
Authors: Lodaya K. , Thiagarajan P. S.
Published: February 2016

This paper introduces a non-interleaved model for the behaviour of distributed computing systems, and an accompanying temporal logic with an explicit treatment of concurrency (based on a notion of local rather than global states).

A subclass of event structures (called n-agent event structures) is used as the underlying model -- intended to describe the computational behaviour of n communicating, sequential (and possibly non-deterministic) agents. The logic is centered around indexed modalities to describe the states of knowledge of the individual agents during such a computation.

An axiom system for the logic is presented, and a full proof of its soundness and completeness (Henkin style proof) is given.
Graphics and Their Grammars
Authors: Hess Lilia , Mayoh Brian H.
Published: February 2016

Graphics are graphs with attributes at their vertices. Graphic grammars are natural extensions of graph and attribute grammars with rules that are attributed extensions of the ''pushout'' productions of graph grammars. The theory of graphic grammars is presented and various programming implementations will be discussed. Many motivating examples will be given, including

the development of biological organisms

 the ''semantic net'' representation of expert system knowledge.
A Distributed Spanning Tree Algorithm
Authors: Johansen Karl Erik , Jørgensen Ulla Lundin , Nielsen Sven Hauge , Nielsen Søren Erik , Skyum Sven
Published: February 2016

We present a distributed algorithm for constructing a spanning tree for connected undirected graphs. Nodes correspond to processors and edges correspond to two-way channels. Each processor has initially a distinct identity and all processors perform the same algorithm. Computation as well as communication is asynchronous. The total number of messages sent during a construction of a spanning tree is at most 2E+3NlogN. The maximal message size is loglogN+log(maxid)+3, where maxid is the maximal processor identity.
The Computational Efficacy of Finite Field Arithmetic
Authors: Frandsen Gudmund Skovbjerg , Sturtivant Carl
Published: February 2016

We show that there exists an interesting non-uniform model of computational complexity within characteristic-two finite fields. This model regards all problems as families of functions whose domain and co-domain are characteristic-two fields. The model is both a structured and a fully general model of computation.

We ask if the same is true when the characteristics of the fields are unbounded. We show that this is equivalent to asking whether arithmetic complexity over the prime fields is a fully general measure of complexity.

We show that this reduces to whether or not a single canonical function is ''easy'' to compute using only modulo p arithmetic.

We show that the arithmetic complexity of the above function is divided between two other canonical functions, the first to be computed modulo p and the second with modulo p^2 arithmetic.

We thus have tied the efficacy of finite field arithmetic to specific questions about the arithmetic complexities of some fundamental functions.
Self-Timed Iteration
Authors: Greenstreet Mark R. , Staunstrup Jørgen , Wililams Ted E.
Published: February 2016

This paper describes a technique for specifying, analyzing and implementing a series of computations using iterative, self-timed circuits. Even though the circuits iterate, they operate without clocking. The circuits do not require arbiters, have no possibility of synchronization failure, and function correctly independent of time delays. Each computation in the iteration can be a general function and is implemented using asynchronous, delay-independent logic which indicates its completion. A general implementation for self-timed iteration is presented; then, simplifying assumptions for specific implementations are shown which can reduce the amount of hardware required.
The BETA Programming Language
Authors: Kristensen Bent Bruun , Madsen Ole Lehrmann , Møller-Pedersen Birger , Nygaard Kristen
Published: February 2016

The BETA programming language is a modern language in the SIMULA 67 tradition. It supports the object-oriented perspective on programming and contains comprehensive facilities for procedural and functional programming. BETA replaces classes, procedures, functions and types by a single abstraction mechanism called the pattern. Patterns may be organized in a classification hierarchy by means of sub-patterns. The notion of virtual procedure is generalized to virtual pattern. Virtual patterns combined with sub-patterns make it possible to delay the specification of an attribute in a pattern. Attributes may then have different bindings in different sub-patterns. BETA also provides a unified framework for sequential, coroutine and concurrent execution.

This paper is a tutorial introduction to BETA.
Block Structure and Object-Oriented Languages
Authors: Madsen Ole Lehrmann
Published: February 2016

Programming languages that support the object-oriented perspective on programming may be divided into two groups. One group of languages originating from Simula follows the Algol tradition with respect to block structure, static name binding and compile-time type checking. Another group of languages originating from Smalltalk is more in the style of the Lisp tradition with a flat set of definitions (classes), dynamic name binding and run-time type checking. The purpose of this paper is to analyze the role of block structure in object-oriented languages. It will be demonstrated that block structure is useful from both a conceptual and technical viewpoint.
Coroutine Sequencing in BETA
Authors: Kristensen Bent Bruun , Møller-Pedersen Birger , Madsen Ole Lehrmann , Nygaard Kristen
Published: February 2016

In the object-oriented perspective a program execution is viewed as a physical model of some real or imaginary part of the world. A programming language supporting the object-oriented perspective must therefore contain comprehensive facilities for modelling phenomena and concepts from the application domain. In object-oriented programming objects model physical material and classes model concepts. By means of subclassing and virtual attributes it is possible to model a hierarchical classification of objects. Many applications in the real world consist of objects carrying out sequential processes. Coroutines may be used for modelling objects that alternate between a number of sequential processes. This paper describes coroutines in BETA.
An Object-Oriented Metaprogramming System
Authors: Madsen Ole Lehrmann , Nørgaard Claus
Published: February 2016

A number of tools in the Mjølner programming environment are metaprograms, i.e. programs that manipulate other programs. The metaprogramming system is grammar based in the sense that a metaprogramming tool may be generated from the grammar of any language. For each syntactic category of the language, a corresponding class is generated. The syntactic hierarchy of the grammar is mapped into a corresponding class hierarchy. This object-oriented representation of programs is further exploited by including a set of more general classes that view a program as an abstract syntax tree and by allowing the user to add semantic attributes in sub-classes.
An Algebraic Model for Bounding Threshold Circuit Depth
Authors: Boyar Joan , Frandsen Gudmund Skovbjerg , Sturtivant Carl
Published: February 2016

We define a new structured and general model of computation: circuits using arbitrary fan- in arithmetic gates over the characteristic two finite fields (F_2n). These circuits have only one input and one output. We show how they correspond naturally to boolean computations with n inputs and n outputs. We show that if circuit sizes are polynomially related then the arithmetic circuit depth and the threshold circuit depth to compute a given function differ by at most a constant factor. We use threshold circuits that allow arbitrary integer weights; however, we show that when compared to the usual threshold model, the depth measure of this generalised model only differs by at most a constant factor (at polynomial size). The fan-in of our arithmetic model is also unbounded in the most generous sense: circuit size is measured as the number of Sum and ½ gates; there is no bound on the number of ''wires'' . We show that these results are provable for any ''reasonable'' correspondance between bit strings of n-bits and elements of F_ 2n. And, we find two distinct characterizations of ''reasonable''. Thus, we have shown that arbitrary fan-in arithmetic computations over F_ 2n constitute a precise abstraction of boolean threshold computations with the pleasant property that various algebraic laws have been recovered.
The Depth Efficacy of Unbounded: Characteristic Finite Field Arithmetic
Authors: Frandsen Gudmund Skovbjerg , Sturtivant Carl
Published: February 2016

We introduce an arithmetic model of parallel computation. The basic operations are ½ and Š gates over finite fields. Functions computed are unary and increasing input size is modelled by shifting the arithmetic base to a larger field. When only finite fields of bounded characteristic are used, then the above model is fully general for parallel computations in that size and depth of optimal arithmetic solutions are polynomially related to size and depth of general (boolean) solutions. In the case of finite fields of unbounded characteristic, we prove that the existence of a fast parallel (boolean) solution to the problem of powering an integer modulo a prime (and powering a polynomial modulo an irreducible polynomial) in combination with the existence of a fast parallel (arithmetic) solution for the problem of computing a single canonical function, f(x), in the prime fields, guarantees the full generality of the finite field model of computation. We prove that the function f(x), has a fast parallel arithmetic solution for any ''shallow'' class of primes, i.e. primes p such that any prime power divisor q of p -1 is bounded in value by a polynomial in log p.
Information Systems Assessment as a Learning Process
Authors: Etzerodt Preben , Madsen Kim Halskov
Published: February 2016

In this paper we emphazise the cognitive and learning aspects of information systems assessment. In doing so we step away from what we consider as the conventional frame work. We elucidate the cognitive and learning aspects by presenting a specific project on information systems assessment. In this project the basic means for fostering a learning process among the participants have been: working groups, focusing on experiences gained by individuals using the information system, using unstructured descriptions to clarify and interpret situations and using specific techniques to uncover and contrast different framings of situations in the organization.
Breakthrough by Breakdown: Metaphors and Structured Domains
Authors: Madsen Kim Halskov
Published: February 2016

In the daily situation of work, the members of an organization usually act without the need to disengage and reflect on their own tasks. But, in the design situation, it becomes important to talk about and reflect on the work. Moreover, it is crucial to set the proper structured domain appropriate for computerization. The message of this paper is that a breakthrough in design may be achieved by conscious use of metaphors. Metaphors may be used to break down the unreflected being of the members of an organization and metaphors may be used for setting of structured domains appropriate for computerization. The basic idea is to understand the organization in terms of other phenomena, whereby knowledge about these phenomena becomes a potential source of inspiration for designing new options. The paper builds its argument around a practical example as well as theoretical work on design and metaphors. The paper is concluded by a set of guidelines for metaphorical design.
Design and Professional Languages
Authors: Andersen Peter Bøgh , Madsen Kim Halskov
Published: February 2016

This paper is about the design of computer systems and the professional language of its users. In the first part of the paper, we present an investigation of the professional language of the three employees at a library. The focus of our attention is the intensive use of metaphors. The investigation supports the idea of using metaphors in design since use of metaphors is one way of relating to the previous experiences of the employees. In the second part of the paper, we present a linguistic approach to design of a computer system. Our approach is related to ideas of K. Nygaard. He has suggested that a careful examination of the professional language of the users should be followed by enriching the professional language through concepts related to informatics. We suggest an approach, not of planned language change, but an approach where the professional language is taken as the starting point for design. We present a concrete way of making a linguistic analysis of the professional language and we show how the linguistic choices may be transposed into a number of design choices. As an illustration of our appraoch, we use the material from the first part of the paper that documents the physical space metaphor.
Anonymous and Verifiable Registration in Databases
Authors: Brandt Jørgen , Damgård Ivan Bjerre , Landrock Peter
Published: February 2016

Methods are given by which personal data about a large number of individuals can be registered in a large central database without having to trust this register not to give away information linked to a given individual. Personal information arriving from many different sources can be placed correctly in the register. The registration is done in a verifiable way: Each individual can be given access to the register to check that his information is correct, and can even, if he chooses to do so, prove to anyone that he is or is not identical to a given person in the register. This can all be done without compromising the anonymity of any other individual.
Programming Environments and System Development Environments
Authors: Sørgaard Pål
Published: February 2016

This report discusses the nature of programming environments and system development environments under the common term development environments. Five dimensions for the characterisation of development environments are identified. These are:
 

 the system development functions supported,

 the kind(s) of work supported,

 the suitability for prototyping,

 the application area, and

 the technical properties of the environments.
 These dimensions are not independent. Some schools or traditions within this field are identified using these dimensions.
It is argued that computer support can be provided for all system development functions. Care must be taken, however, to allow for the necessary interplay between the different system development functions. Technical properties like integration, incrementality, and tailorability may support this interplay. They may also lead to a change in the role of programming in system development. Programming will become more integrated in all parts of system development. This will make the classical division of work between analyst and programmers less obvious.
Neural Networks With Complex Connection Matrices
Authors: Szilagyi Miklos
Published: February 2016

The concept of neural networks is generalized to include complex connections between the network's units. The similarity between the dynamics of some linear complex networks and the quantum mechanical behaviour of atomic systems is shown.
Unified Algebras and Modules
Authors: Mosses Peter D.
Published: February 2016

This paper concerns the algebraic specification of abstract data types. It introduces and motivates the recently-developed framework of unified algebras, and provides a practical notation for their modular specification. It also compares unified algebras with the well known framework of order-sorted algebras, with underlies of OBJ specification language.
Designing for a Dollar a Day
Authors: Kyng Morten
Published: February 2016

This paper is about the kind of tools and techniques that are accessible to resource weak groups for use in design and evaluation of computer support. ''Resource weak'' means in this connection, that the economic power and the ablity to control the ''local enviroment'' of the group i limited. The human resources of such groups are often (potentially) strong, but restrained by the organization of work and society; and although the tools are cheap the activities are demanding in terms of human resources. This kind of work should be seen as a supplement to participation in desing processes controlled by others. When end users participate in projects set up by managenemt, these ''lay'' designers often lack familiarity wigh the tools and techniques, they lack the power and resoutces to influence the choice of questions to be considered, and they are not the ones deciding how to utilize the results of a design project when actually changing the workplace.

To give the context of the work on which the paper is based, I first describe the Scandinavian tradition of trade union based end user participation in systems development. Then I discuss some of the issues involved in improving the conditions for independent end user design activities. I go on by presenting a set of ''cheap tools'' and techniques, including the use mock-up's. This set covers the issues of establishing the possibility of alternatives, of creating visions of new and different uses of technology, and of designing computer support. A central question in relation to the tools and techniques, is their accessibility to end users, and I discuss this based on the notions of family resemblance and ''hands-on'' experience.
The Application of Claw Free Functions in Cryptography: - Unconditional Protection in Cryptographic Protocols
Authors: Damgård Ivan Bjerre
Published: February 2016

A set of clawfree functions is a set of functions that are all easily computable, but for which it is hard to simultaneously find preimages of an element under different functions. In this thesis we develop a formalism for describing such functions, and show several techniques for building them, some new and others well known. We show how clawfree functions can be extremely useful, in the construction of for example collision free hash functions and of cryptographic protocols in general. In particular, we show how to solve the famous multiparty computation problem, while achieving un conditional privacy protection for one participant. This is the optimal result in the model of communication we consider.
Unified Algebras and Action Semantics
Authors: Mosses Peter D.
Published: February 2016

The recently-developed framework of Unified Algebras is intended for axiomatic specification of abstract data types. In contrast, the somewhat older framework of Action Semantics (earlier known as ''Abstract Semantic Algebras'') is for denotational specification of programming languages. This paper gives an introduction to the main features of Unified Algebras and Action Semantics, and discusses the relation between them. The two frameworks both exploit nondeterministic choice in unconventional ways.
Reusability and Tailorability in the Mjølner BETA System
Authors: Nørgaard Claus , Sandvad Elmer
Published: February 2016

Reusability and tailorability in software development are discussed in general and a set of techniques supporting these concepts are described. An important concept that can give a high degree of reusability as well as tailorability is generality. Object-oriented languages give good support for expressing generality. The techniques discussed in this paper have been developed during the construction of the Mjølner BETA System. Some of them are of general (language independent) character but a great part of the flexibility in the system is due to the BETA programming language. An exception handling technique is presented as a special kind of tailoring. A general communication model supporting integration and tailorability of software components is presented.
Optimal detection of query injectivity
Authors: Schwartzbach Michael I. , Larsen Kim Skak
Published: February 2016

Most unary relational database operators can be described through functions from tuples to tuples. Injectivity of the specified function ensures that no duplicates are created in the relational result. This normally reduces the complexity of the query from O(r log r) to O(r), where r is the number of tuples in the argument relation.

 

We consider functions obtained as terms over a general signature. The semantic properties of the operators are specified by Horn clauses generalizing functional dependencies. Relative to such specifications, we present an optimal algorithm for detecting injectivity of unary queries. The complexity of this algorithm is linear in the size of the query.

 

It turns out that relational functional dependencies are very easily incorporated into this framework. As a further result, we provide a Horn clause characterization of the functional dependencies that can be propagated to the result relation.
A simple algorithm for computing the smallest enclosing circle
Authors: Skyum Sven
Published: February 2016

We present a simple iterative algorithm for computing the smallest enclosing circle and the farthest-point Voronoi diagram of a pointset and the ordinary Voronoi diagram of a convex polygon. The algorithm(s) takes O(n log n) time for n points. This is not optimal for any of the problems, but the simplicity of the algorithm(s) makes it a better alternative for medium sized problems than earlier published methods.