waashk/acm huggingface dataset:
on liouvillian solutions of homogeneous linear differential equations  this paper deals with the problem of finding liouvillian solutions of an nth order homogeneous linear differential equation l(y)=0 with coefficients in a differential field k whose field of constants is c. for second order linear differential equations such an algorithm has been given by j. kovacic and implemented. a general decision procedure for finding liouvillian solutions of nth order equations has been given by m.f. singer, but the resulting algorithm, although constructive, is not in implementable form even for second order equations. the algorithm uses the fact that, if l(y)=0 has a liouvillian solution, then, l(y)=0 has a solution z such that u=z′/z is algebraic over k, which means that l(y) has a solution z of the form e u, where u is algebraic over k. since the logarithmic derivative u=z′/z of a solution z is a solution of the riccati equation r(y)=0 associated to l(y)=0, the problem thus reduces to find an algebraic solution u of r(y)=0. this task is now split into two parts:  to find the set deg(n) of possible degrees n for the minimal polynomial p(x)=0 of u over k.  to compute, for each possible degree of p(x), the possible coefficients of p(x).  if we denote c(ii) the complexity of the second step and #deg(n) the size of the set deg(n), we see that the complexity of the whole procedure is of the form c(ii)#deg(n) and thus exponential in #deg(n). this shows that the only way to make the procedure effective is to get sharp bounds on the size of the set deg(n), which is the scope of this paper.  initially, we construct, using representation theory of linear groups, a set deg(n) where all n are of bounded size and only divisible by a small set of primes. because of the divisibility condition the size of the set deg(n) is asymptotically small. we derive the upper bound 2n4*π(n+1) for #deg(n), where n is the degree of l(y)=0 and π(n) denotes the number of primes less or equal to n. this improves the bound of #deg(n) from jordan's theorem. the bound on the size of the primes that divide n is also a bound for the primes that divide the algebraic degree of the logarithmic derivative of at least one solution of l(y)=0. from the conditions on the size of the primes, some structure of the differential galois group can also be derived. next, we study the action of the differential galois group on u to get sharp bounds for #deg(n). the resulting set deg(n) is the best possible one for n=2 and probably small enough to allow an implementation of the singer-algorithm for n=3. we show that, for an algebraic solution u of r(u)=0, the degree n of the minimal polynomial p(x) of u equals the size of the orbit of u under the action of the differential galois group of l(y)=0. we then bound the size of the orbit of u by a value that can be effectively computed from a classification of the finite subgroups of pgl(n,c).  f. ulmer j. calmet
illuminating micro geometry based on precomputed visibility  many researchers have been arguing that geometry, bump maps, and brdfs present a hierarchy of detail that should be exploited for efficient rendering purposes. in practice however, this is often not possible due to inconsistencies in the illumination for these different levels of detail. for example, while bump map rendering often only considers direct illumination and no shadows, geometry- based rendering and brdfs will mostly also respect shadowing effects, and in many cases even indirect illumination caused by scattered light.  in this paper, we present an approach for overcoming these inconsistencies. we introduce an inexpensive method for consistently illuminating height fields and bump maps, as well as simulating brdfs based on precomputed visibility information. with this information we can achieve a consistent illumination across the levels of detail.  the method we propose offers significant performance benefits over existing algorithms for computing the light scattering in height fields and for computing a sampled brdf representation using a virtual gonioreflectometer. the performance can be further improved by utilizing graphics hardware, which then also allows for interactive display.  finally, our method also approximates the changes in illumination when the height field, bump map, or brdf is applied to a surface with a different curvature.  wolfgang heidrich katja daubert jan kautz hans-peter seidel
octree based assembly sequence generation  this paper describes a system for the automatic recognition of assembly features and the generation of assembly/disassembly sequences. the paper starts by reviewing the nature and use of assembly features. one of the conclusions drawn from this survey is that the majority of assembly features involve sets of spatially adjacent faces. two principle types of adjacency relationships are identified and an algorithm is presented for identifying assembly features which arise from "_spatial_" and "_contact_" face adjacency relationships (known as _s-adjacency_ and _c-adjacency_ respectively).  the algorithm uses an octree representation of a b-rep model to support the geometric reasoning required to locate assembly features on disjoint bodies. a pointerless octree representation is generated by recursively sub-dividing the assembly model's bounding box into octants which are used to locate:    * those portions of faces which are _c-adjacent_ (i.e. they effectively touch within the tolerance of the octree).    * those portions of faces which are _s-adjacent_ to a nominated face.  the resulting system can locate and partition spatially adjacent faces in a wide range of situations and a different resolutions. the assembly features located are recorded as attributes in the b-rep model and are then used to generate a disassembly sequence plan for the assembly. this sequence plan is represented by a _transition state tree_ which incorporates knowledge of the availability of feasible gripping features.  by way of illustration, the algorithm is applied to several trial components  raymond c. w. sung jonathan r. corney doug e. r. clark
robotics: the new automation tool  industrial robots have seen limited use by industries for over a decade but until the auto industry introduced robotics for spot welding applications in the late 60s the robot was not considered seriously. now they are readily accepted throughout industry. the reasons for their current popularity are the rapidly increasing costs of labor and the seemingly declining productivity of todays workers. in addition, robots today are credited for additional product and quality improvements not seriously considered in the past. benefits similar to those that have long been attributes associated with hard automation.  this paper looks at robotics from a users viewpoint and addresses some of the benefits and concerns attributable to their use. to this end, this paper will describe several applications that are currently used in production with results relative to production gains, side benefits and operator acceptance.  harold r. marcotte
progressive compression for lossless transmission of triangle meshes  lossless transmission of 3d meshes is a very challenging and timely problem for many applications, ranging from collaborative design to engineering. additionally, frequent delays in transmissions call for progressive transmission in order for the end user to receive useful successive refinements of the final mesh. in this paper, we present a novel, fully progressive encoding approach for lossless transmission of triangle meshes with a very fine granularity. a new valence-driven decimating conquest, combined with patch tiling and an original strategic retriangulation is used to maintain the regularity of valence. we demonstrate that this technique leads to good mesh quality, near-optimal connectivity encoding, and therefore a good rate-distortion ratio throughout the transmission. we also improve upon previous lossless geometry encoding by decorrelating the normal and tangential components of the surface. for typical meshes, our method compresses connectivity down to less than 3.7 bits per vertex, 40% better in average than the best methods previously reported [5, 18]; we further reduce the usual geometry bit rates by 20% in average by exploiting the smoothness of meshes. concretely, our technique can reduce an ascii vrml 3d model down to 1.7% of its size for a 10-bit quantization (2.3% for a 12-bit quantization) while providing a very progressive reconstruction.  pierre alliez mathieu desbrun
the physiology of prolog expert system inference engine  the current literature on expert systems development in prolog is replete with sample inference engines. however, the available models tend to be fragmentary and simplistic. important issues such as how to incorporate arithmetic evaluation into the reasoning process are often ignored. therefore, we present and describe a more realistic prolog expert system inference engine.  the inference engine is an enhanced version of a standard model. it includes features and employs techniques that are non- existent in current models. we give special consideration to the relationship that the inference engine bears to the underlying prolog engine. the role of unification and sld resolution in the life of a prolog expert system inference engine is also discussed.  david roach hal berghel
multi-dimensional input techniques and articulated figure positioning by multiple constraints  a six degree-of-freedom input device presents some novel possibilities for manipulating and positioning three-dimensional objects. some experiments in using such a device in conjunction with a real- time display are described. a particular problem which arises in positioning an articulated figure is the solution of three-dimensional kinematics subject to multiple joint position goals. a method using such an input device to interactively determine positions and a constraint satisfaction algorithm which simultaneously achieves those constraints is described. examples which show the power and efficiency of this method for key-frame animation positioning are demonstrated.  norman i. badler kamran h. manoochehri david baraff
real-time animation and motion capture in web human director (whd)  motion capture systems usually work in conjunction with complex 3d applications, such as 3d studio max by kinetix or maya by alias/wavefront. once models have been created in these applications, motion capture systems provide the necessary data input to animate these models. the context of this paper introduces a simple motion capture system, which is integrated into a web-based application, thus allowing hanim humanoids to be animated using vrml and java. since web browser/vrml plugin context is commonly available on computers, the presented motion capture application is easy to use on any platform. taking benefit of a standard language as vrml makes the exploitation of produced animation easier than other commercial application with their specific formats.  christian babski daniel thalmann
toward adding knowledge to learning algorithms for indexing legal cases  case-based reasoning systems have shown great promise for legal argumentation, but their development and wider availability are still slowed by the cost of manually representing cases. in this paper, we present our recent progress toward automatically indexing legal opinion texts for a cbr system. our system smile uses a classification-based approach to find abstract fact situations in legal texts. to reduce the complexity inherent in legal texts, we take the individual sentences from a marked-up collection of case summaries as examples. we illustrate how integrating a legal thesaurus and linguistic information with a machine learning algorithm can help to overcome the difficulties created by legal language. the paper discusses results from a preliminary experiment with a decision tree learning algorithm. experiments indicate that learning on the basis of sentences, rather than full documents, is effective. they also confirm that adding a legal thesaurus to the learning algorithm leads to improved performance for some, but not all, indexing concepts.  stefanie bruninghaus kevin d. ashley
data filtering for automatic classification of rocks from reflectance spectra the ability to identify the mineral composition of rocks and soils is an important tool for the exploration of geological sites. for instance, nasa intends to design robots that are sufficiently autonomous to perform this task on planetary missions. spectrometer readings provide one important source of data for identifying sites with minerals of interest. reflectance spectrometers measure intensities of light reflected from surfaces over a range of wavelengths. spectral intensity patterns may in some cases be sufficiently distinctive for proper identification of minerals or classes of minerals. for some mineral classes, carbonates for example, specific short spectral intervals are known to carry a distinctive signature. finding similar distinctive spectral ranges for other mineral classes is not an easy problem. we propose and evaluate data-driven techniques that automatically search for spectral ranges optimized for specific minerals. in one set of studies, we partition the whole interval of wavelengths available in our data into sub- intervals, or bins, and use a genetic algorithm to evaluate a candidate selection of subintervals. as alternatives to this computationally expensive search technique, we present an entropy-based heuristic that gives higher scores for wavelengths more likely to distinguish between classes, as well as other greedy search procedures. results are presented for four different classes, showing reasonable improvements in identifying some, but not all, of the mineral classes tested. jonathan moody ricardo silva joseph vanderwaart
design-time simulation of a large-scale, distributed object system  we present a case study in using simulation at design time to predict the performance and scalability properties of a large-scale distributed object system. the system, called consul, is a network management system designing to support hundreds of operators managing millions of network devices. it is essential that a system such as consul be designed with performance and scalability in mind, but due to consul's complexity and scale, it is hard to reason about performance and scalability using ad hoc techniques. we built a simulation of consul's design to guide the design process by enabling performanace and scalability analysis of various design alternatives. a major challenge in doing design-time simulation is that many parameters for the simulation are based on estimates rather than measurements. we developed analysis methods that derive conclusions that are valid in the presence of estimation errors. in this article, we describe our scalability analysis method for design simulations of distributed object systems. the main idea is to use relative and comparative reasoning to analyze design alternatives and compare transaction behaviors. we demonstrate the analysis approach by describing its application to consul.  svend frølund pankaj garg
delta's virtual physics laboratory (case study): a comprehensive learning platform on physics astronomy  perhaps the most effective instrument to simplify and to clarify the comprehension of any complex mathematical or scientific theory is through visualisation. moreover using interactivity & 3d real time representations, one can easily explore and hence learn quickly in the virtual environments. the concept of virtual and safe laboratories has vast potentials in education. with the aid of computer simulations & 3d visualisations, many dangerous or cumbersome experiments may be implemented in the virtual environments, with rather small effort. nonetheless visualisation alone is of little use if the respective simulation is not scientifically accurate. hence a rigours combination of precise computation as well as sophisticated visualisation, presented through some intuitive user interface is required to realise a virtual laboratory for education. here we introduce delta's virtual physics laboratory, comprising of a wide range of applications in the field of physics & astronomy, which can be implemented and used as an interactive learning tool on the world wide web.  sepideh chakaveh udo zlender detlef skaley konstantinos fostiropoulos dieter breitschwerdt
high performance presence-accelerated ray casting  we present a novel presence acceleration for volumetric ray casting. a highly accurate estimation for object presence is obtained by projecting all grid cells associated with the object boundary on the image plane. memory space and access time are reduced by run-length encoding of the boundary cells, while boundary cell projection time is reduced by exploiting projection templates and multiresolution volumes. efforts have also been made towards a fast perspective projection as well as interactive classification. we further present task partitioning schemes for effective parallelization of both boundary cell projection and ray traversal procedures. good load balancing has been reached by taking full advantage of both the optimizations in the serial rendering algorithm and shared-memory architecture. our experimental results on a 16-processor sgi power challenge have shown interactive rendering rates for 2563 volumetric data sets at 10 - 30 hz. this paper describes the theory and implementation of our algorithm, and shows its superiority over the shear- warp factorization approach.  ming wan arie kaufman steve bryson
the effect of synchronization requirements on the performance of distributed simulations  recent experiments have shown that conservative methods can achieve good performance by exploiting the characteristics of the system being simulated. in this paper we focus on the interrelationship between run time and synchronization requirements of a distributed simulation. a metric that considers the effect of lookahead and the physical rate of transmission of messages, and an arrival approximation that models the effect of synchronization requirements on the run time are developed. it is shown that even when good lookahead is exploited in the system, poor run-time performance is achieved if an inefficient mapping of lps to processors is used.  murali s. shanker b. eddy patuwo
concurrent simulation: an alternative to distributed simulation  the advent of a new generation of multiprocessors allows new approaches to parallel simulation. previous work in this area has concentrated on distributed simulation; this approach uses spatial decomposition to allow simulations to be run on networks of machines, where the message flow between processors in the network is related closely to the topology of the system being simulated. this paper presents an alternate approach, concurrent simulation, which is based on temporal decomposition. this allows natural use to be made of the shared memory facilities and load-balancing capabilities of the new multiprocessors, and it overcomes some fundamental limitations of the distributed approach.  douglas w. jones
autostereoscopic displays and computer graphics autostereoscopic displays present a three-dimensional image to a viewer without the need for glasses or other encumbering viewing aids. three classes of autostereoscopic displays are described: reimaging displays, volumetric displays and parallax displays. reimaging displays reproject an existing three-dimensional object to a new location or depth. volumetric displays illuminate points in a spatial volume. parallax displays emit directionally varying image information into the viewing zone. parallax displays are the most common autostereoscopic displays and are most compatible with computer graphics. different display technologies of the three types are described. computer graphics techniques useful for three-dimensional image generation are outlined. michael halle
an agent-oriented multiagent planning system  this paper describes a multiagent planning system, mupac, that formulates cooperative plans efficiently. it contains three features: meta-level planning, breakable and unbreakable action representations, and an integrated agent screening and assignment procedure. the meta-level planning transforms an original goal statement into a skeletal plan, which is easier to follow and helps reduce the chance of conflicts at low-level actions. the breakable/unbreakable action representation specifies specific agent-action requirements. it also specifies concurrency and cooperation possibilities among actions. it makes plan generation and agent assignment straight forward, thus reducing the reasoning time of finding parallelism and cooperation among agents. the integrated agent screening and assignment procedure formulates plans following the skeletal plan. the performance of mupac has been discussed along four aspects: planning efficiency, planning flexibility, agent cooperation, and plan quality. results have shown that significant improvement has been achieved.  kai-hsiung chang william b. day suebskul phiphobmongkol
a simulation model of a wheat elevator system using slam  this paper shows that simulation can be used as an analytical tool for agricultural marketing and the potential of the slam simulation language to model such systems. this analysis shows the effects upon the elevator complex from two different harvest season scenarios. the model also has the versatility of being able to derive the effects of different decision strategies on the elevator complex without designing a totally different model. the effects of elevator breakdowns, building of more elevator storage facilities, smaller and larger dumping areas, and different initial elevator inventory levels can be easily investigated. also, different elevator systems (country, terminal, and export) can be developed from the existing model.  thomas r. harris behrokh khoshnevis
performance of clustering algorithms on time-dependent spatial patterns  a single linkage clustering algorithm adapted for points distributed over time (slot) is used to recover clusters from coplanar points associated with time parameters. cluster number and shape determine separability and hence effectiveness of the algorithm. performance in simulation experiments also depended on the probability of recording cluster points. slot links points observed at different times if they are within some limiting distance, and the distance parameter becomes critical when detectability is low. performance comparisons are made with other algorithms, and results are presented in the context of a rule-based expert system for solving problems involving cluster analysis of time-dependent spatial patterns.  ben pinkowski
lester: using paradigm cases in a quasi-precedential legal domain  we are developing lester (legal expert system for termination of employment review), a case-based reasoning program to advise in the area of unjust discharge from employment under collective bargaining agreements. lester uses paradigm cases to reason in a legal domain that is not governed by a strong concept of precedent. this paper describes the domain and gives an overview of the current version of the program.  k. a. lambert m. h. grunewald
a multiple cooperating intelligent agents project progress repost  the multiple cooperating agents project (mcap) at east stroudsburg university will be described. mcap is an ongoing set of experiments in artificial intelligence designed around a set of up to four cooperating robots. the tool manipulating robots operate in a world of workbenches, screws, nails, screwdrivers and hammers. natural language, english, is used as the human interface. research is underway in natural language recognition and generation, interaction of intelligent agents, modeling, planning and activity execution. system architecture will be discussed as well as the current status of those integrated subsystems making up the kernel. implementation data and future plans also will be presented.  richard d. amori