Lothar Hotz | University of Hamburg (original) (raw)

Papers by Lothar Hotz

1 Product Configuration Systems (PCSs) are automatic solutions to support and facilitate sales an... more 1 Product Configuration Systems (PCSs) are automatic solutions to support and facilitate sales and engineering processes. PCSs are among the most successful applications of expert system technology and one of the drivers in the digitalization era. Therefore, there are several studies on the benefits of PCS. Such studies are, however, often relatively undetailed or unspecific about the costs and benefits of such projects. To address this issue, this paper presents studies of four PCS projects, which quantify benefits in terms of reduced working hours, and the costs in terms of development, implementation, and maintenance costs. The studies of the PCS projects each concern a 3-year utilization period. Our results show that the gained benefits from PCS has a growing trend over the years in case of proper maintenance. We also demonstrate the opposite is the case if not properly maintaining the PCSs. Furthermore, the study reveals that PCSs with the constant maintenance grow increasingly...

Intelligent Applications for Monitoring and Security

The authors describe a generic framework for model-based behaviour interpretation and its applica... more The authors describe a generic framework for model-based behaviour interpretation and its application to monitoring aircraft service activities. Behaviour models are represented in a standardised conceptual knowledge base using OWL-DL for concept definitions and the extension SWRL for constraints. The conceptual knowledge base is automatically converted into an operational scene interpretation system implemented in Java and JESS that accepts tracked objects as input and delivers high-level activity descriptions as output. The interpretation process employs Beam Search for exploring the interpretation space, guided by a probabilistic rating system. The probabilistic model cannot be efficiently represented in the ontology, but it has been designed to closely correspond to the compositional hierarchy of behaviour concepts. Experiments are described that demonstrate the system performance with real airport data.

In this paper, we demonstrate an application of rules in a business process scenario. As business... more In this paper, we demonstrate an application of rules in a business process scenario. As business processes, we consider data-intensive applications which need to move huge data files from server to server. By using the Business Process Model and Notation (BPMN) in our application, we enable clearly and hierarchically represented business processes. Such modeled processes can automatically be executed in a distributed environment with the Jadex open source middleware. Furthermore, the process execution is monitored with declarative rules, also implemented with Jadex. The demonstration shows the start of BPMNmodeled processes and their execution monitoring through logs and rules.

In this paper, we combine MOF-based software representations and description logic-based mechanis... more In this paper, we combine MOF-based software representations and description logic-based mechanisms for facilitating software reuse. All software representations (requirements specifications, design models, code) arising from one project are combined in a software case and stored in a repository for later retrieval. For reuse purposes, we use requirements as search indexes. We map metamodel-based requirements specifications to an ontology and use a Description Logic reasoner for classification. This makes implicit taxonomical relations explicit. The inferred taxonomical hierarchy is then used to compute the taxonomical similarity between the current (initial) requirements and those in the repository. Doing so, we retrieve software cases with a high reuse potential. This approach has already been validated in an industrial context.

ECAI 2006 Workshop on Configuration, 2006

Abstract. This paper presents a conceptual framework that allows the configuration of aggregates ... more Abstract. This paper presents a conceptual framework that allows the configuration of aggregates using existing parts observed in reality. Typical problems that can be solved with such an approach are recognition problems that construct aggregates from given ...

Proceedings of the Workshop on Software …, 2004

Abstract. In this paper, we discuss the use of structure-based configuration methods for deriving... more Abstract. In this paper, we discuss the use of structure-based configuration methods for deriving products in the context of software product lines. Modeling techniques for features, artifacts as well as procedural knowledge and inference methods are presented and ...

The group "Planen / Scheduling und Konfigurieren / Entwerfen" at the faculty FB 1 of the GI ("Ges... more The group "Planen / Scheduling und Konfigurieren / Entwerfen" at the faculty FB 1 of the GI ("Gesellschaft für Informatik") combines researchers and practitioners of the areas of planning, scheduling and configuration, and design and affords a collective forum for exchange of evaluations and experiences. The fields of these areas have many features in common and are often tackled by similar technologies. However, the communities do not overlap and joint meetings are rather rare. The PuKworkshop is such a joint meeting and provides the possibility for the exchange of ideas, concepts and problems between researchers from the areas mentioned. The PuK-2003 is the 17 th in a series of annual workshops started in 1987. In this time it has taken place in conjunction with diverse conferences, such as XPS-93, XPS-97, XPS-99, ECAI-2000 and KI-2001. Similar to earlier workshops there is a focus on one specific area. This year, part of the workshop will be specially focused on Configuration of Software. In that context we received papers on topics such as configuration of embedded systems using knowledge about the structure and state behaviour of the configuration objects, modelling architectural variability, evolution of configuration models and navigation in the process of selecting configuration objects. In addition to this specific focus, there are also papers on planning and scheduling. All contributions are arranged in sessions that bundle similar topics, containing 3 paper dealing with planning, 4 papers about scheduling and 4 papers on configuration. The 11 contributions of this workshop demonstrate the wide range of applicable AI techniques as well as the similarities in problem solving technologies of the tackled fields. Two additional papers present state-of-the-art and new challenges of configuration and planning. A large number of papers are written in English. Papers from The Netherlands, Great Britain, France and Spain present collaborations of the German configuration and planning community with other European research groups and underline the growing international character of the workshop.

Vorträgen des 22. PuK-Workshops (der jährliche Workshop der Fachgruppe „Planen/

In der Dissertation „Frame-basierte Wissensrepräsentation zur Konfigurierung, Analyse und Diagnos... more In der Dissertation „Frame-basierte Wissensrepräsentation zur Konfigurierung, Analyse und Diagnose technischer Systeme“ [5] wird eine für die drei traditionellen KI-Aufgaben gemeinsame Wissensrepräsentation herausgearbeitet und an verschiedenen Anwendungsgebieten exemplarisch verdeutlicht. Weiterhin wird für eine effektive Verarbeitung eine neue parallele Programmierweise entwickelt – die strukturorientierte parallele Programmierung. Ihre Verwendung wird anhand der KI-Aufgaben skizziert.

Proceedings of the International Conference on Knowledge Engineering and Ontology Development, 2011

In knowledge engineering, ontology creation, and especially in knowledge-based configuration ofte... more In knowledge engineering, ontology creation, and especially in knowledge-based configuration often used relations are: aggregate relations (has-parts, here called structural relations), specialization relation (is-a), and instantiation (instance-of). A combination of the later is called metaization, which denotes the use of multiple instantiation layers. Structural and specialization relations are mainly used for organizing the knowledge represented on one layer. Instantiation layers model different kind of knowledge, i.e. knowledge about sets, individuals, and knowledge about knowledge (metaknowledge). By applying reasoning techniques on each layer, reasoning on metaknowledge is enabled.

One way to improve the robustness and flexibility of robot performance is to let the robot learn ... more One way to improve the robustness and flexibility of robot performance is to let the robot learn from its experiences. In this paper, we describe the architecture and knowledge-representation framework for a service robot being developed in the EU project RACE, and present examples illustrating how learning from experiences will be achieved. As a unique innovative feature, the framework combines memory records of low-level robot activities with ontology-based high-level semantic descriptions.

Knowledge-Based Configuration

No part of this publication may be reproduced or transmitted in any form or by any means, electro... more No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher's permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this fi eld are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

Abstract. In this paper, we combine MOF-based software representa-tions and description logic-bas... more Abstract. In this paper, we combine MOF-based software representa-tions and description logic-based mechanisms for facilitating software reuse. All software representations (requirements specifications, design models, code) arising from one project are combined in a so-called soft-ware case and stored in a repository for later retrieval. For reuse pur-poses, we use requirements as search indexes. We map metamodel-based requirements specifications to an ontology and use a Description Logic reasoner for classification. This makes implicit taxonomical relations ex-plicit. The inferred taxonomical hierarchy is then used to compute the taxonomical similarity between the current (initial) requirements and those in the repository. Doing so, we retrieve software cases with a high reuse potential. This approach has already been validated in an industrial context. 1

Abstract: In this paper, we point out the role of sequences of samples for training an incrementa... more Abstract: In this paper, we point out the role of sequences of samples for training an incremental learning method. We define characteristics of incremental learning methods to describe the influence of sample ordering on the performance of a learned model. We show the influence of sequence for two different types of incremental learning. One is aimed on learning structural models, the other on learning models to discriminate object classes. In both cases, we show the possibility to find good sequences before starting the training. 1

International Conference on Agents and Artificial Intelligence, 2010

Recognizing structure is an important aspect of interpreting many computer vision domains. Struct... more Recognizing structure is an important aspect of interpreting many computer vision domains. Structure can manifest itself both visually, in terms of repeated low-level phenomena, and conceptually, in terms of a highlevel compositional hierarchy. In this paper, we demonstrate an approach for combining a low-level repetitive structure detector with a logical high-level interpretation system. We evaluate the performance on a set of images from the building façade domain.

1 Product Configuration Systems (PCSs) are automatic solutions to support and facilitate sales an... more 1 Product Configuration Systems (PCSs) are automatic solutions to support and facilitate sales and engineering processes. PCSs are among the most successful applications of expert system technology and one of the drivers in the digitalization era. Therefore, there are several studies on the benefits of PCS. Such studies are, however, often relatively undetailed or unspecific about the costs and benefits of such projects. To address this issue, this paper presents studies of four PCS projects, which quantify benefits in terms of reduced working hours, and the costs in terms of development, implementation, and maintenance costs. The studies of the PCS projects each concern a 3-year utilization period. Our results show that the gained benefits from PCS has a growing trend over the years in case of proper maintenance. We also demonstrate the opposite is the case if not properly maintaining the PCSs. Furthermore, the study reveals that PCSs with the constant maintenance grow increasingly...

Intelligent Applications for Monitoring and Security

The authors describe a generic framework for model-based behaviour interpretation and its applica... more The authors describe a generic framework for model-based behaviour interpretation and its application to monitoring aircraft service activities. Behaviour models are represented in a standardised conceptual knowledge base using OWL-DL for concept definitions and the extension SWRL for constraints. The conceptual knowledge base is automatically converted into an operational scene interpretation system implemented in Java and JESS that accepts tracked objects as input and delivers high-level activity descriptions as output. The interpretation process employs Beam Search for exploring the interpretation space, guided by a probabilistic rating system. The probabilistic model cannot be efficiently represented in the ontology, but it has been designed to closely correspond to the compositional hierarchy of behaviour concepts. Experiments are described that demonstrate the system performance with real airport data.

In this paper, we demonstrate an application of rules in a business process scenario. As business... more In this paper, we demonstrate an application of rules in a business process scenario. As business processes, we consider data-intensive applications which need to move huge data files from server to server. By using the Business Process Model and Notation (BPMN) in our application, we enable clearly and hierarchically represented business processes. Such modeled processes can automatically be executed in a distributed environment with the Jadex open source middleware. Furthermore, the process execution is monitored with declarative rules, also implemented with Jadex. The demonstration shows the start of BPMNmodeled processes and their execution monitoring through logs and rules.

In this paper, we combine MOF-based software representations and description logic-based mechanis... more In this paper, we combine MOF-based software representations and description logic-based mechanisms for facilitating software reuse. All software representations (requirements specifications, design models, code) arising from one project are combined in a software case and stored in a repository for later retrieval. For reuse purposes, we use requirements as search indexes. We map metamodel-based requirements specifications to an ontology and use a Description Logic reasoner for classification. This makes implicit taxonomical relations explicit. The inferred taxonomical hierarchy is then used to compute the taxonomical similarity between the current (initial) requirements and those in the repository. Doing so, we retrieve software cases with a high reuse potential. This approach has already been validated in an industrial context.

ECAI 2006 Workshop on Configuration, 2006

Abstract. This paper presents a conceptual framework that allows the configuration of aggregates ... more Abstract. This paper presents a conceptual framework that allows the configuration of aggregates using existing parts observed in reality. Typical problems that can be solved with such an approach are recognition problems that construct aggregates from given ...

Proceedings of the Workshop on Software …, 2004

Abstract. In this paper, we discuss the use of structure-based configuration methods for deriving... more Abstract. In this paper, we discuss the use of structure-based configuration methods for deriving products in the context of software product lines. Modeling techniques for features, artifacts as well as procedural knowledge and inference methods are presented and ...

The group "Planen / Scheduling und Konfigurieren / Entwerfen" at the faculty FB 1 of the GI ("Ges... more The group "Planen / Scheduling und Konfigurieren / Entwerfen" at the faculty FB 1 of the GI ("Gesellschaft für Informatik") combines researchers and practitioners of the areas of planning, scheduling and configuration, and design and affords a collective forum for exchange of evaluations and experiences. The fields of these areas have many features in common and are often tackled by similar technologies. However, the communities do not overlap and joint meetings are rather rare. The PuKworkshop is such a joint meeting and provides the possibility for the exchange of ideas, concepts and problems between researchers from the areas mentioned. The PuK-2003 is the 17 th in a series of annual workshops started in 1987. In this time it has taken place in conjunction with diverse conferences, such as XPS-93, XPS-97, XPS-99, ECAI-2000 and KI-2001. Similar to earlier workshops there is a focus on one specific area. This year, part of the workshop will be specially focused on Configuration of Software. In that context we received papers on topics such as configuration of embedded systems using knowledge about the structure and state behaviour of the configuration objects, modelling architectural variability, evolution of configuration models and navigation in the process of selecting configuration objects. In addition to this specific focus, there are also papers on planning and scheduling. All contributions are arranged in sessions that bundle similar topics, containing 3 paper dealing with planning, 4 papers about scheduling and 4 papers on configuration. The 11 contributions of this workshop demonstrate the wide range of applicable AI techniques as well as the similarities in problem solving technologies of the tackled fields. Two additional papers present state-of-the-art and new challenges of configuration and planning. A large number of papers are written in English. Papers from The Netherlands, Great Britain, France and Spain present collaborations of the German configuration and planning community with other European research groups and underline the growing international character of the workshop.

Vorträgen des 22. PuK-Workshops (der jährliche Workshop der Fachgruppe „Planen/

In der Dissertation „Frame-basierte Wissensrepräsentation zur Konfigurierung, Analyse und Diagnos... more In der Dissertation „Frame-basierte Wissensrepräsentation zur Konfigurierung, Analyse und Diagnose technischer Systeme“ [5] wird eine für die drei traditionellen KI-Aufgaben gemeinsame Wissensrepräsentation herausgearbeitet und an verschiedenen Anwendungsgebieten exemplarisch verdeutlicht. Weiterhin wird für eine effektive Verarbeitung eine neue parallele Programmierweise entwickelt – die strukturorientierte parallele Programmierung. Ihre Verwendung wird anhand der KI-Aufgaben skizziert.

Proceedings of the International Conference on Knowledge Engineering and Ontology Development, 2011

In knowledge engineering, ontology creation, and especially in knowledge-based configuration ofte... more In knowledge engineering, ontology creation, and especially in knowledge-based configuration often used relations are: aggregate relations (has-parts, here called structural relations), specialization relation (is-a), and instantiation (instance-of). A combination of the later is called metaization, which denotes the use of multiple instantiation layers. Structural and specialization relations are mainly used for organizing the knowledge represented on one layer. Instantiation layers model different kind of knowledge, i.e. knowledge about sets, individuals, and knowledge about knowledge (metaknowledge). By applying reasoning techniques on each layer, reasoning on metaknowledge is enabled.

One way to improve the robustness and flexibility of robot performance is to let the robot learn ... more One way to improve the robustness and flexibility of robot performance is to let the robot learn from its experiences. In this paper, we describe the architecture and knowledge-representation framework for a service robot being developed in the EU project RACE, and present examples illustrating how learning from experiences will be achieved. As a unique innovative feature, the framework combines memory records of low-level robot activities with ontology-based high-level semantic descriptions.

Knowledge-Based Configuration

No part of this publication may be reproduced or transmitted in any form or by any means, electro... more No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher's permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this fi eld are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

Abstract. In this paper, we combine MOF-based software representa-tions and description logic-bas... more Abstract. In this paper, we combine MOF-based software representa-tions and description logic-based mechanisms for facilitating software reuse. All software representations (requirements specifications, design models, code) arising from one project are combined in a so-called soft-ware case and stored in a repository for later retrieval. For reuse pur-poses, we use requirements as search indexes. We map metamodel-based requirements specifications to an ontology and use a Description Logic reasoner for classification. This makes implicit taxonomical relations ex-plicit. The inferred taxonomical hierarchy is then used to compute the taxonomical similarity between the current (initial) requirements and those in the repository. Doing so, we retrieve software cases with a high reuse potential. This approach has already been validated in an industrial context. 1

Abstract: In this paper, we point out the role of sequences of samples for training an incrementa... more Abstract: In this paper, we point out the role of sequences of samples for training an incremental learning method. We define characteristics of incremental learning methods to describe the influence of sample ordering on the performance of a learned model. We show the influence of sequence for two different types of incremental learning. One is aimed on learning structural models, the other on learning models to discriminate object classes. In both cases, we show the possibility to find good sequences before starting the training. 1

International Conference on Agents and Artificial Intelligence, 2010

Recognizing structure is an important aspect of interpreting many computer vision domains. Struct... more Recognizing structure is an important aspect of interpreting many computer vision domains. Structure can manifest itself both visually, in terms of repeated low-level phenomena, and conceptually, in terms of a highlevel compositional hierarchy. In this paper, we demonstrate an approach for combining a low-level repetitive structure detector with a logical high-level interpretation system. We evaluate the performance on a set of images from the building façade domain.