Heuristics for constructing while loops

AbstractWe discuss the stepwise construction of iterative programs from specifications, represented by relations. We make an effort to isolate, in the construction of an iterative program, those decisions that are dictated by correctness preservation concerns, from decisions that the programmer is free to make at will

Program Repair by Stepwise Correctness Enhancement

Relative correctness is the property of a program to be more-correct than another with respect to a given specification. Whereas the traditional definition of (absolute) correctness divides candidate program into two classes (correct, and incorrect), relative correctness arranges candidate programs on the richer structure of a partial ordering. In other venues we discuss the impact of relative correctness on program derivation, and on program verification. In this paper, we discuss the impact of relative correctness on program testing; specifically, we argue that when we remove a fault from a program, we ought to test the new program for relative correctness over the old program, rather than for absolute correctness. We present analytical arguments to support our position, as well as an empirical argument in the form of a small program whose faults are removed in a stepwise manner as its relative correctness rises with each fault removal until we obtain a correct program.Comment: In Proceedings PrePost 2016, arXiv:1605.0809

Program Derivation by Correctness Enhacements

Relative correctness is the property of a program to be more-correct than another program with respect to a given specification. Among the many properties of relative correctness, that which we found most intriguing is the property that program P' refines program P if and only if P' is more-correct than P with respect to any specification. This inspires us to reconsider program derivation by successive refinements: each step of this process mandates that we transform a program P into a program P' that refines P, i.e. P' is more-correct than P with respect to any specification. This raises the question: why should we want to make P' more-correct than P with respect to any specification, when we only have to satisfy specification R? In this paper, we discuss a process of program derivation that replaces traditional sequence of refinement-based correctness-preserving transformations starting from specification R by a sequence of relative correctness-based correctness-enhancing transformations starting from abort.Comment: In Proceedings Refine'15, arXiv:1606.0134

Harnessing a Refinement Theory to Compute Loop Functions

AbstractWe consider a while loop on some space S and we are interested in deriving the function that this loop defines between its initial states and its final states (when it terminates). Such a capability is useful in a wide range of applications, including reverse engineering, software maintenance, program comprehension, and program verification. In the absence of a general theoretical solution to the problem of deriving the function of a loop, we explore engineering solutions. In this paper we use a relational refinement calculus to approach this complex problem in a systematic manner. Our approach has many drawbacks, some surmountable and some not (being inherent to the approach); nevertheless, it offers a way to automatically derive the function of loops or an approximation thereof, under some conditions

Karakteristik batugamping Formasi Wapulaka dan pemanfaatannya sebagai bahan galian industri di Desa Wuna, Kabupaten Muna, Sulawesi Tenggara

Daerah penelitian merupakan kawasan karst yang tersusun atas batugamping terumbu berumur Plistosen. Secara administrasi, daerah penelitian terletak pada Desa Wuna, Kabupaten Muna, Sulawesi Tenggara. Hamparan batugamping terumbu tidak hanya dapat dimanfaatkan dalam geokonservasi, namun juga sebagai bahan industri. Metode yang digunakan adalah metode lapangan geologi dan pekerjaan laboratorium dengan data luaran utama adalah deskripsi sayatan tipis batugamping dan kandungan senyawa mayor batugamping. Pengolahan data lapangan menggunakan analisis petrografi dalam pemerian batuan dan analisis geokimia senyawa mayor untuk mengetahui jenis pemanfaatan batugamping. Batugamping dijumpai pada satuan perbukitan karst dan pedataran. Litologi penyusun berupa wackestone dan packstone yang kaya akan fragmen bioclast, kalsit, aragonit, mineral sekunder, dan porositas yang intens. Batugamping didominasi oleh CaO (kalsium oksida) dengan kadar rata-rata 94,44%. Beberapa sampel memiliki kadar MgO (magnesium oksida) tinggi hingga mencapai 4,4% yang mengindikasikan proses dolomitisasi. Data geokimia menunjukkan batugamping dapat digunakan untuk berbagai keperluan bahan industri seperti: industri semen, bata silika, soda abu, karbit, dan pemurnian baja. Batugamping packstone dan wackstone untuk bahan industri dicirikan oleh kelimpahan lumpur karbonat dan aragonit, serta minimnya mineral sekunder

Power System Dynamic State Estimation: Motivations, Definitions, Methodologies, and Future Work

This paper summarizes the technical activities of the Task Force on Power System Dynamic State and Parameter Estimation. This Task Force was established by the IEEE Working Group on State Estimation Algorithms to investigate the added benefits of dynamic state and parameter estimation for the enhancement of the reliability, security, and resilience of electric power systems. The motivations and engineering values of dynamic state estimation (DSE) are discussed in detail. Then, a set of potential applications that will rely on DSE is presented and discussed. Furthermore, a unified framework is proposed to clarify the important concepts related to DSE, forecasting-aided state estimation, tracking state estimation, and static state estimation. An overview of the current progress in DSE and dynamic parameter estimation is provided. The paper also provides future research needs and directions for the power engineering community