Taming Numbers and Durations in the Model Checking Integrated Planning System

The Model Checking Integrated Planning System (MIPS) is a temporal least commitment heuristic search planner based on a flexible object-oriented workbench architecture. Its design clearly separates explicit and symbolic directed exploration algorithms from the set of on-line and off-line computed estimates and associated data structures. MIPS has shown distinguished performance in the last two international planning competitions. In the last event the description language was extended from pure propositional planning to include numerical state variables, action durations, and plan quality objective functions. Plans were no longer sequences of actions but time-stamped schedules. As a participant of the fully automated track of the competition, MIPS has proven to be a general system; in each track and every benchmark domain it efficiently computed plans of remarkable quality. This article introduces and analyzes the most important algorithmic novelties that were necessary to tackle the new layers of expressiveness in the benchmark problems and to achieve a high level of performance. The extensions include critical path analysis of sequentially generated plans to generate corresponding optimal parallel plans. The linear time algorithm to compute the parallel plan bypasses known NP hardness results for partial ordering by scheduling plans with respect to the set of actions and the imposed precedence relations. The efficiency of this algorithm also allows us to improve the exploration guidance: for each encountered planning state the corresponding approximate sequential plan is scheduled. One major strength of MIPS is its static analysis phase that grounds and simplifies parameterized predicates, functions and operators, that infers knowledge to minimize the state description length, and that detects domain object symmetries. The latter aspect is analyzed in detail. MIPS has been developed to serve as a complete and optimal state space planner, with admissible estimates, exploration engines and branching cuts. In the competition version, however, certain performance compromises had to be made, including floating point arithmetic, weighted heuristic search exploration according to an inadmissible estimate and parameterized optimization

Probabilistic Hybrid Action Models for Predicting Concurrent Percept-driven Robot Behavior

This article develops Probabilistic Hybrid Action Models (PHAMs), a realistic causal model for predicting the behavior generated by modern percept-driven robot plans. PHAMs represent aspects of robot behavior that cannot be represented by most action models used in AI planning: the temporal structure of continuous control processes, their non-deterministic effects, several modes of their interferences, and the achievement of triggering conditions in closed-loop robot plans. The main contributions of this article are: (1) PHAMs, a model of concurrent percept-driven behavior, its formalization, and proofs that the model generates probably, qualitatively accurate predictions; and (2) a resource-efficient inference method for PHAMs based on sampling projections from probabilistic action models and state descriptions. We show how PHAMs can be applied to planning the course of action of an autonomous robot office courier based on analytical and experimental results

Reasoning about Actions with Temporal Answer Sets

In this paper we combine Answer Set Programming (ASP) with Dynamic Linear Time Temporal Logic (DLTL) to define a temporal logic programming language for reasoning about complex actions and infinite computations. DLTL extends propositional temporal logic of linear time with regular programs of propositional dynamic logic, which are used for indexing temporal modalities. The action language allows general DLTL formulas to be included in domain descriptions to constrain the space of possible extensions. We introduce a notion of Temporal Answer Set for domain descriptions, based on the usual notion of Answer Set. Also, we provide a translation of domain descriptions into standard ASP and we use Bounded Model Checking techniques for the verification of DLTL constraints.Comment: To appear in Theory and Practice of Logic Programmin

Matematički modeli za višekriterijumske procene u sistemima učenja na daljinu

Učenje na daljinu (eng. Distance Learning System - DLS) je sveprisutniji savremeni koncept obrazovanja. To je koncept zasnovan na tutorskom sistemu i njegovim modulima (moduli asistenta, tutora, moduli za praćenje i prepoznavanje emocija, motivacije, itd.) koji deluju u korelaciji sa povratnim informacijama iz sistema. Ova modularnost značajna je pre svega u korektivnoj ulozi, adaptivnom kapacitetu, automatizaciji i samoregulaciji DL sistema. Novi koncept DL sistema omogućio je lakše uvođenje, široku zastupljenost i veću funkcionalnost savremenih sistema za upravljanje učenjem (eng. Learning Management System - LMS). LMS sistemi koriste se za kreiranje, organizaciju, realizaciju, administraciju, verifikaciju kurseva u skladu sa obrazovnim okruženjem. Definisanje okruženja i priprema za nastavu počinje prepoznavanjem karakteristika studenata, nastavne grupe, podelom u podgrupe po orjentaciji, predznanju, predispozicijama, odnosno prepoznavanju idividualnih karakteristika, sklonosti i mogućnosti studenata. Pristupanjem kursu, tokom kursa, a posebno pri rešavanju problemskih zadataka, dolazi do nejasnoća i nerazumevanja, razvijaju se različite emocije, padovi koncentracije, motivacije, i sl. Tada DL sistem i pripadajući moduli moraju signalzirati nepravilnosti i slabosti koncepta učenja u skladu sa individualnim potrebama, a uz pomoć modula korektivnih funkcija prevazilaziti ih. Iz tog razloga vrlo je važno u startu indetifikovati validne činioce obrazovnog okruženja i karakteristike studenta. U skladu stim neophodno je grupi/pojedincu dodeliti adektavtan skupa modula DL sistemu za uspešno praćenje kursa i kvalitetne procene uspešnosti okončanja kursa. Različitost činioca koji definišu okruženje neophodno je definisati težinskim faktorom, obzorom na posledične efekte. Dakle, neophodno je izraditi matematičke modele za ocenjivanje rada studenata koji studiraju na daljinu, na osnovu ulaznih parametara sa jedne strane (opšti uspeh, uspeh iz srodnih predmeta prethodnog nivoa školovanja, motivisanost studenta za studije, i sl.), te na osnovu reakcija tokom kursa na zadate probleme i zadatke, dobijenih u cilju uspešnog savlađivanja gradiva, sa druge strane. Takođe, neophodno je izraditi matematičke modele višekriterijumskog (VK) ocenjivanja odgovarajućih platformi za DL studije sa ciljem da se odredi za date situacije odgovarajući način održavanja nastave za pojedine studente ili grupe. Prosta primena poznatih metoda VKA ponekad nije moguća, zbog same strukture metoda. Dakle, u cilju postizanja odgovarajućih rezultata, razvija se prilagođeni VK metoda za ocenjivanje za kokretni slučaj, tj. za kokretno obrazovno okruženje

Service-oriented IT-Systems for Highly Flexible Business Processes

Der vorliegende Band „Dienstorientierte IT-Systeme für hochflexible Geschäftsprozesse“ enthält ausgewählte Ergebnisse des Forschungsverbundes forFLEX aus den Jahren 2008 - 2011. Ausgehend von einer Charakterisierung des Forschungsfeldes und zwei fallstudienbasierten Anwendungsszenarien werden Fragen der Analyse, der Modellierung und Gestaltung sowie der Infrastruktur, Sicherheit und Werkzeugunterstützung von hochflexiblen Geschäftsprozessen und ihrer Unterstützung durch dienstorientierte IT-Systeme untersucht. Das Buch wendet sich an IT-Fach- und Führungskräfte in Wirtschaft und Verwaltung sowie an Wissenschaftler, die an der Analyse und Gestaltung von Flexibilitätspotenzialen (teil-) automatisierter Geschäftsprozesse interessiert sind