Look-ahead with mini-bucket heuristics for MPE

The paper investigates the potential of look-ahead in the con-text of AND/OR search in graphical models using the Mini-Bucket heuristic for combinatorial optimization tasks (e.g., MAP/MPE or weighted CSPs). We present and analyze the complexity of computing the residual (a.k.a Bellman update) of the Mini-Bucket heuristic and show how this can be used to identify which parts of the search space are more likely to benefit from look-ahead and how to bound its overhead. We also rephrase the look-ahead computation as a graphical model, to facilitate structure exploiting inference schemes. We demonstrate empirically that augmenting Mini-Bucket heuristics by look-ahead is a cost-effective way of increasing the power of Branch-And-Bound search.Postprint (published version

Residual-guided look-ahead in AND/OR search for graphical models

We introduce the concept of local bucket error for the mini-bucket heuristics and show how it can be used to improve the power of AND/OR search for combinatorial optimization tasks in graphical models (e.g. MAP/MPE or weighted CSPs). The local bucket error illuminates how the heuristic errors are distributed in the search space, guided by the mini-bucket heuristic. We present and analyze methods for compiling the local bucket-errors (exactly and approximately) and show that they can be used to yield an effective tool for balancing look-ahead overhead during search. This can be especially instrumental when memory is restricted, accommodating the generation of only weak compiled heuristics. We illustrate the impact of the proposed schemes in an extensive empirical evaluation for both finding exact solutions and anytime suboptimal solutions.Peer ReviewedPostprint (published version

The Application of Material Requirements Planning (MRP) System to Aircraft Parts Inventory

As the title implies, the application of MRP into an aviation context is the response to the huge cost of parts holding in an ever-expanding industry. The nature of intermittent parts demand (unpredictable parts), typical of maintenance and overhaul inventory parts control, is investigated both to illustrate the deficiency of traditional ROP systems for dependent-demand inventory and other applications in the area of lot sizing and forecasting with a specific exploration into sources of demand lumpiness. In order to investigate current inventory procedure, we surveyed 175 airline operators and maintenance service organisations, to explore the status of MRP and ROP worldwide. This response showed current inventory practice to be less than effective and that better systems were required, leading us to investigate specific problems experienced namely; lot-size and forecasting methods used within the MRP concept. MRP had made some inroads into the aviation sector, but a number of factors have prevented its general uptake. Through a case study of KTM-uk’s workshop practices within overhaul and repair, we apply various solutions to lot-size and forecasting methodology in order to realise best practice, putting forward a small scale MRP-spreadsheet as a working tool. In the process we present two predictive models; a Lot-size Predictive Cost Model. LPCM, and a Predictive Error-Forecasting Model, PEFM. The models in their present form use seventeen lot-size and thirteen forecasting methods respectively, simplifying material management through appropriate estimates of costs and planning needs. Within lotsizing, we found that under almost all operations conditions the WWA and MSM2 methods give the best performance. Similarly the WMA method followed by the Holt and the Croston methods work best for forecasting intermittent demand parts

Look-ahead with mini-bucket heuristics for MPE

The paper investigates the potential of look-ahead in the con-text of AND/OR search in graphical models using the Mini-Bucket heuristic for combinatorial optimization tasks (e.g., MAP/MPE or weighted CSPs). We present and analyze the complexity of computing the residual (a.k.a Bellman update) of the Mini-Bucket heuristic and show how this can be used to identify which parts of the search space are more likely to benefit from look-ahead and how to bound its overhead. We also rephrase the look-ahead computation as a graphical model, to facilitate structure exploiting inference schemes. We demonstrate empirically that augmenting Mini-Bucket heuristics by look-ahead is a cost-effective way of increasing the power of Branch-And-Bound search

Persuasion in selected Sesotho drama texts

Thesis (DLitt (African Languages))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: This study examined persuasion in selected drama texts from the literary period 1981 to 2006. The selection was organised through the examination of two such texts in each of the following three periods: • 1981–1989: Le ka nketsang and Mpowane • 1990–1999: Bana ba khomo tsa batho and Tsiketsing sa qomatsi • 2000–2006: Ha le fahloe habeli and Leholimo la phetloa Since persuasion is a relatively new topic in literature, particularly in African languages, the study examined the persuasion strategies used in the selected texts. These strategies either entail persuasion applied purely as an upfront aspect for changing the targets’ attitudes, behaviours, beliefs or opinions or entail certain situations during which the persuaders, as literary characters, employ another type (or types) of persuasion – coercion, manipulation or propaganda – in order to change the targets. The main thrust of this thesis was the persuasive tactics or techniques that might be applied by literary characters in an attempt to stimulate change in other literary characters. The study also examined whether additional persuasive interactions are employed to motivate change in others and whether counter-persuasive actions are employed to resist the proposed change. Chapter One introduces the aspect of persuasion as propounded by persuasion practitioners and experts and gives the framework of the study as a whole. Chapter Two initiates the literature review on the goals-plans-action (GPA) model as part of the psychological theories on persuasive messages produced by various interactants. This model presupposes reasons for persuaders to create certain plans for achieving their goals. Chapter Three is concerned with Le ka nketsang and Mpowane as the selected 1981 to 1989 drama texts. Chapter Four concentrates on Bana ba khomo tsa batho and Tsiketsing sa qomatsi from the 1990 to 1999 literary period. Chapter Five deals with the literary period 2000 to 2006 and analyses the two drama texts Ha le fahloe habeli and Leholimo la phetloa. Chapter Six draws a conclusion from the findings on persuasive strategies and makes observations, per chapter, on the persuasive attempts from each literary period.AFRIKAANSE OPSOMMING: Hierdie studie het oorreding in geselekteerde dramatekste uit die letterkundige tydperk 1981 tot 2006 ondersoek. Die seleksie is georganiseer deur twee sodanige tekste in elk van die onderstaande drie tydperke te ondersoek: • 1981–1989: Le ka nketsang en Mpowane • 1990–1999: Bana ba khomo tsa batho en Tsiketsing sa qomatsi • 2000–2006: Ha le fahloe habeli en Leholimo la phetloa Aangesien oorreding relatief nuwe onderwerp in die letterkunde is, in die besonder in Afrikatale, het die studie ondersoek ingestel na die oorredingstrategieë wat in die geselekteerde tekste gebruik is. Hierdie strategieë behels óf oorreding wat toegepas word suiwer as spontane aspek vir verandering van die houdings, gedrag, oortuigings of menings van die teikens, óf dit behels sekere situasies waartydens die oorreders, as letterkundige karakters, ander soort (of soorte) oorreding – dwang, manipulering of propaganda – gebruik ten einde die teikens te verander. Die belangrikste dryfkrag van hierdie tesis was die oorredende taktieke of tegnieke wat deur letterkundige karakters toegepas kan word in poging om verandering in ander letterkundige karakters aan te moedig. Die studie het ook nagegaan of addisionele oorredende interaksies ingespan word om verandering in ander te motiveer en of teen-oorredende optrede gebruik word om weerstand te bied teen die voorgestelde verandering. Hoofstuk Een stel die aspek van oorreding bekend soos dit by oorredingspraktisyns en deskundiges aangebied word, en gee die raamwerk van die studie as geheel. Hoofstuk Twee onderneem die literatuurstudie oor die doelstellings-planne-optrede (DPO)-model as deel van die sielkundige teorieë oor oorredende boodskappe soos gelewer deur verskeie persone wat in interaksie tree. Hierdie model voorveronderstel redes vir oorreders om sekere planne te ontwikkel vir die bereiking van hulle doelstellings. Hoofstuk Drie word gewy aan Le ka nketsang en Mpowane as die geselekteerde dramatekste uit die tydperk 1981 tot 1989. Hoofstuk Vier konsentreer op Bana ba khomo tsa batho en Tsiketsing sa qomatsi uit die tydperk 1990 tot 1999. Hoofstuk Vyf dek die letterkundige tydperk 2000 tot 2006, en analiseer die twee dramatekste Ha le fahloe habeli en Leholimo la phetloa. Hoofstuk Ses kom tot gevolgtrekking na aanleiding van die bevindings oor oorredende strategieë en maak waarnemings, per hoofstuk, oor die oorredende pogings van elke letterkundige tydperk

Fifth Conference on Artificial Intelligence for Space Applications

The Fifth Conference on Artificial Intelligence for Space Applications brings together diverse technical and scientific work in order to help those who employ AI methods in space applications to identify common goals and to address issues of general interest in the AI community. Topics include the following: automation for Space Station; intelligent control, testing, and fault diagnosis; robotics and vision; planning and scheduling; simulation, modeling, and tutoring; development tools and automatic programming; knowledge representation and acquisition; and knowledge base/data base integration

Research and technology, 1990: Goddard Space Flight Center

Goddard celebrates 1990 as a banner year in space based astronomy. From above the Earth's obscuring atmosphere, four major orbiting observatories examined the heavens at wavelengths that spanned the electromagnetic spectrum. In the infrared and microwave, the Cosmic Background Explorer (COBE), measured the spectrum and angular distribution of the cosmic background radiation to extraordinary precision. In the optical and UV, the Hubble Space Telescope has returned spectacular high resolution images and spectra of a wealth of astronomical objects. The Goddard High Resolution Spectrograph has resolved dozens of UV spectral lines which are as yet unidentified because they have never before been seen in any astronomical spectrum. In x rays, the Roentgen Satellite has begun returning equally spectacular images of high energy objects within our own and other galaxies