scholarly journals Compositional learning of mutually recursive procedural systems

Author(s):  
Markus Frohme ◽  
Bernhard Steffen

AbstractThis paper presents a compositional approach to active automata learning of Systems of Procedural Automata (SPAs), an extension of Deterministic Finite Automata (DFAs) to systems of DFAs that can mutually call each other. SPAs are of high practical relevance, as they allow one to efficiently learn intuitive recursive models of recursive programs after an easy instrumentation that makes calls and returns observable. Key to our approach is the simultaneous inference of individual DFAs for each of the involved procedures via expansion and projection: membership queries for the individual DFAs are expanded to membership queries of the entire SPA, and global counterexample traces are transformed into counterexamples for the DFAs of concerned procedures. This reduces the inference of SPAs to a simultaneous inference of the DFAs for the involved procedures for which we can utilize various existing regular learning algorithms. The inferred models are easy to understand and allow for an intuitive display of the procedural system under learning that reveals its recursive structure. We implemented the algorithm within the LearnLib framework in order to provide a ready-to-use tool for practical application which is publicly available on GitHub for experimentation.

Author(s):  
Serge Miguet ◽  
Annick Montanvert ◽  
P. S. P. Wang

Several nonclosure properties of each class of sets accepted by two-dimensional alternating one-marker automata, alternating one-marker automata with only universal states, nondeterministic one-marker automata, deterministic one-marker automata, alternating finite automata, and alternating finite automata with only universal states are shown. To do this, we first establish the upper bounds of the working space used by "three-way" alternating Turing machines with only universal states to simulate those "four-way" non-storage machines. These bounds provide us a simplified and unified proof method for the whole variants of one-marker and/or alternating finite state machine, without directly analyzing the complex behavior of the individual four-way machine on two-dimensional rectangular input tapes. We also summarize the known closure properties including Boolean closures for all the variants of two-dimensional alternating one-marker automata.


2020 ◽  
Vol 67 ◽  
pp. 881-903
Author(s):  
Hana Chockler ◽  
Pascal Kesseli ◽  
Daniel Kroening ◽  
Ofer Strichman

We propose to use algorithms for learning deterministic finite automata (DFA), such as Angluin’s L* algorithm, for learning a DFA that describes the possible scenarios under which a given program error occurs. The alphabet of this automaton is given by the user (for instance, a subset of the function call sites or branches), and hence the automaton describes a user-defined abstraction of those scenarios. More generally, the same technique can be used for visualising the behavior of a program or parts thereof. It can also be used for visually comparing different versions of a program (by presenting an automaton for the behavior in the symmetric difference between them), and for assisting in merging several development branches. We present experiments that demonstrate the power of an abstract visual representation of errors and of program segments, accessible via the project’s web page. In addition, our experiments in this paper demonstrate that such automata can be learned efficiently over real-world programs. We also present lazy learning, which is a method for reducing the number of membership queries while using L*, and demonstrate its effectiveness on standard benchmarks.


Author(s):  
Emmanuel Sin ◽  
He Yin ◽  
Murat Arcak

Abstract We present a distributed control law to assemble a cluster of satellites into an equally-spaced, planar constellation in a desired circular orbit about a planet. We assume each satellite only uses local information, transmitted through communication links with neighboring satellites. The same control law is used to maintain relative angular positions in the presence of disturbance forces. The stability of the constellation in the desired orbit is proved using a compositional approach. We first show the existence and uniqueness of an equilibrium of the interconnected system. We then certify each satellite and communication link is equilibrium-independent passive with respective storage functions. By leveraging the skew symmetric coupling structure of the constellation and the equilibrium-independent passivity property of each subsystem, we show that the equilibrium of the interconnected system is stable with a Lyapunov function composed of the individual subsystem storage functions. We further prove that the angular velocity of each satellite converges to the desired value necessary to maintain circular, areostationary orbit. Finally, we present simulation results to demonstrate the efficacy of the proposed control law in acquisition and station-keeping of an equally-spaced satellite constellation in areostationary orbit despite the presence of unmodeled disturbance forces.


Author(s):  
Duangui Wang

Formulation of the problem. An analysis of the genre-dramaturgical patterns in a poorly studied composition by the Chinese composer Zhao Jiping (2011) has been proposed. The relevance of the topic and the novelty of the received results of the genre-semantic analysis of the chosen vocal cycle are concluded in the search for the definition dictated by the artistic concept of its author – a cantata-type vocal poem (a small choir is introduced into the score). Among its criteria there are reliance on the orchestral accompaniment, the timbre variation of each song of the cycle, the poetry dictated by the presence of the image of the Poet, the symbolization of the poetic and intonation language, the cultural chronotope uniting the Time of History and its inclusion into the culture of the 21st century. The purpose of the article is to perform a genre-semantic analysis of “The Eight Songs” for Zhao Jiping’s voice and orchestra and to identify the main sound-image concepts of “the Chinese world view” that make up the drama of the vocal cycle. Analysis of the recent publications on the topic. In the second half of the 20th century, a new compositional approach to organizing vocal songs into a whole, poemness, appeared. In the articles by A. Belonenko (about “Petersburg” by G. Sviridov) and T. Zharkikh (about “Poemes pour Mi” by O. Messiaen), the research emphasis is placed on other problems of the organization of the vocal whole. For the first time, in the conditions of the poly-timbre vocal and orchestral synthesis and the national picture of the world poemness becomes the subject of a special interest of the singer-researcher. Research methods: the structural-functional analysis concerns the components of the composer’s text (the vocal melody and textural and timbre thematism of the orchestral part); the semantic one – reveals the symbolism of poetic texts; the genre analysis – aims to identify the individual interpretation of typical models of vocal music. The presentation of the main material. The poem principle became the embodiment of the author’s desire to unite several vocal miniatures into a single musical universe based on the common concept – the image of the Poet. The philosophical and religious feelings and thoughts contained in the texts chosen by the composer reflect not only his worldview, but also the national mentality and psychology of the world view of the “Chinese world view” (the chronotope of History). This rare quality of poetry – to unite the personality (I) and society (We) into a single “national image of the world” – is the essence of the symbolism of the ancient Chinese poetry of the Tang era. The desire to individualize the timbre composition in each of the parts of the cycle is a characteristic feature of many vocal and instrumental compositions of the 20th century. However, in Zhao Jiping’s work, the search for diversity acts simultaneously with the desire to preserve the timbre constants. As such, with this composer this role is represented by a string and bow group, as the carrier of the song beginning, which performs the function of the instrumental “nimbus” (more rarely, of the dialogue-counterpoint) in relation to the singer. In contrast to Western composers, Zhao Jiping does not seek to use “pure” timbres: vocals and xiao can be duplicated with the wind and plucked strings. The composer does not look for contrasting timbres in search of the associative community: on the contrary, he creates single-timbre groups (pipa + guzheng + harp, triangle + bells + cymbals) to vary the shades of the poetic text. Their “consonance” is close to assonance in poetry (from assono – “I sound in tune”), which in the musical context creates the timbre assonance. The symphonic instruments are combined in timbre groups (string, wind), and the ethnic often perform an individualized function (for example, guzheng with its irregular glissando in No. 2–4 gives a national flavour). The orchestral density, along with the gradual “academic turning” of timbres, increases from the second half of the sound of the cycle (No. 5) to the final. Xiao is replaced by the wind and brass (with No. 5), while the ethnic plucked is replaced by the harp. The gradual increase in the timbre multidimensionality of the texture also has the “opposite effect”, since it is combined with the enhancement of the timbre contrast in the final parts of the cycle and as a result of the “aggravation” of the chamberness. The most chamber part is number 6, where the brass is for the first time silenced, and only the pipa and guzheng are heard. The culmination of the “chamberness” is in the first stanza of the final: a duet of the voice and harp. Conclusion. The vocal-instrumental synthesis in the poem genre, identified in Zhao Jiping’s “The Eight Songs”, is characterized by the organic interaction of the national and European principles of musical thinking. The performers are faced with complex technical and psychological tasks that require a developed orchestral-timbre hearing, intellectualism and associative thinking. A vocal-instrumental poem is a way of modelling spiritual reality, in which the unity of time and space is manifested due to the poetic text, in which the integral sense-image of the Poet acts, personifying the sound-like concepts of the culture of its time and the history of an entire people (“national view of the world”), their “inclusion” into the musical chronotope of the 21st century.


Author(s):  
Akira Ito ◽  
Katsushi Inoue ◽  
Yue Wang

Several nonclosure properties of each class of sets accepted by two-dimensional alternating one-marker automata, alternating one-marker automata with only universal states, nondeterministic one-marker automata, deterministic one-marker automata, alternating finite automata, and alternating finite automata with only universal states are shown. To do this, we first establish the upper bounds of the working space used by "three-way" alternating Turing machines with only universal states to simulate those "four-way" non-storage machines. These bounds provide us a simplified and unified proof method for the whole variants of one-marker and/or alternating finite state machine, without directly analyzing the complex behavior of the individual four-way machine on two-dimensional rectangular input tapes. We also summarize the known closure properties including Boolean closures for all the variants of two-dimensional alternating one-marker automata.


Author(s):  
C.N. Sun

The present study demonstrates the ultrastructure of the gingival epithelium of the pig tail monkey (Macaca nemestrina). Specimens were taken from lingual and facial gingival surfaces and fixed in Dalton's chrome osmium solution (pH 7.6) for 1 hr, dehydrated, and then embedded in Epon 812.Tonofibrils are variable in number and structure according to the different region or location of the gingival epithelial cells, the main orientation of which is parallel to the long axis of the cells. The cytoplasm of the basal epithelial cells contains a great number of tonofilaments and numerous mitochondria. The basement membrane is 300 to 400 A thick. In the cells of stratum spinosum, the tonofibrils are densely packed and increased in number (fig. 1 and 3). They seem to take on a somewhat concentric arrangement around the nucleus. The filaments may occur scattered as thin fibrils in the cytoplasm or they may be arranged in bundles of different thickness. The filaments have a diameter about 50 A. In the stratum granulosum, the cells gradually become flatted, the tonofibrils are usually thin, and the individual tonofilaments are clearly distinguishable (fig. 2). The mitochondria and endoplasmic reticulum are seldom seen in these superficial cell layers.


Author(s):  
Anthony J. Godfrey

Aldehyde-fixed chick retina was embedded in a water-containing resin of glutaraldehyde and urea, without dehydration. The loss of lipids and other soluble tissue components, which is severe in routine methods involving dehydration, was thereby minimized. Osmium tetroxide post-fixation was not used, lessening the amount of protein denaturation which occurred. Ultrathin sections were stained with 1, uranyl acetate and lead citrate, 2, silicotungstic acid, or 3, osmium vapor, prior to electron microscope examination of visual cell outer segment ultrastructure, at magnifications up to 800,000.Sections stained with uranyl acetate and lead citrate (Fig. 1) showed that the individual disc membranes consisted of a central lipid core about 78Å thick in which dark-staining 40Å masses appeared to be embedded from either side.


Author(s):  
Anthony A. Paparo ◽  
Judith A. Murphy

The purpose of this study was to localize the red neuronal pigment in Mytilus edulis and examine its role in the control of lateral ciliary activity in the gill. The visceral ganglia (Vg) in the central nervous system show an over al red pigmentation. Most red pigments examined in squash preps and cryostat sec tions were localized in the neuronal cell bodies and proximal axon regions. Unstained cryostat sections showed highly localized patches of this pigment scattered throughout the cells in the form of dense granular masses about 5-7 um in diameter, with the individual granules ranging from 0.6-1.3 um in diame ter. Tissue stained with Gomori's method for Fe showed bright blue granular masses of about the same size and structure as previously seen in unstained cryostat sections.Thick section microanalysis (Fig.l) confirmed both the localization and presence of Fe in the nerve cell. These nerve cells of the Vg share with other pigmented photosensitive cells the common cytostructural feature of localization of absorbing molecules in intracellular organelles where they are tightly ordered in fine substructures.


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