Development of knowledge representation based on markov logical networks in the business process mangement system

Досліджено проблему побудови представлення знань в системі процесного управління на основі аналізу поведінки бізнес-процесів, що представлена у вигляді логів подій. Кожна подія характеризує дію бізнес-процесу. Актуальність проблеми визначається тим, що при управлінні складними знання-ємними бізнес-процесами виконавці можуть змінювати послідовність дій з урахуванням додаткових знань про предметну область. В результаті виникає невідповідність між процесом та його моделлю, що створює труднощі для подальшого управління бізнес-процесом. Для усунення вказаної невідповідності потрібно формалізувати ці додаткові знання та використовувати їх при процесному управлінні, що потребує створення відповідного представлення знань. Запропоновано модель представлення знань враховує статичні й динамічні характеристики бізнес-процесу. Статичні характеристики бізнес-процесу задаються фактами та правилами із аргументами, представленими атрибутами подій логу. Факти і правила формуються на основі відповідних шаблонів. Атрибути задають значення властивостей об’єктів, з якими оперує бізнес-процес. Динамічні особливості бізнес-процесу визначаються через поточний розподіл ймовірностей виконання правил з урахуванням атрибутів поточної події логу бізнес-процесу. Запропонована модель відрізняється тим, що вона враховує обмеження на допустимі послідовності виконання дій бізнес-процесу, а також обмеження на основі апріорних знань про предметну область. Такі обмеження дозволить понизити складність задачі пошуку ймовірностей успішного завершення бізнес-процесу шляхом скорочення множини допустимих трас в тому випадку, якщо виконавці змінили послідовність дій. В практичному аспекті модель забезпечує можливість підтримки прийняття рішень з управління знання-ємними бізнес-процесами на основі прогнозування ймовірностей досягнення кінцевого стану процесу з урахуванням атрибутів подій логу.The problem of constructing knowledge representation in the process control system based on the analysis of the behavior of business processes, represented in the form of logs of events, is studied. Each event characterizes the action of the business process. The urgency of the problem is determined by the fact that when managing complex knowledge-capacious business processes, performers can change the sequence of actions taking into account additional knowledge about the subject area. As a result, there is a discrepancy between the process and its model, which creates difficulties for the further management of this business process. To eliminate this discrepancy, it is necessary to formalize the additional knowledge used and apply them in process management, which requires the creation of an appropriate knowledge representation. The proposed knowledge representation model takes into account the static and dynamic characteristics of the business process. The static characteristics of a business process are specified by facts and rules with arguments represented by the attributes of the log events. Facts and rules are formed on the basis of appropriate templates. Attributes specify the values of the properties of objects with which the business process operates. Dynamic features of the business process are determined through the current distribution of the probability that the rules will be executed, taking into account the attributes of the current business process log event. The proposed model is characterized by the fact that it takes into account the limitations on the permissible sequences of execution of the actions of the business process, as well as restrictions based on a priori knowledge of the subject area. Such restrictions will reduce the complexity of the problem of finding the probabilities of a successful completion of a business process by reducing the number of allowed trails in the event that the performers have changed the sequence of actions. In practical terms, the model provides the ability to support decision-making on the management of knowledge-intensive business processes based on predicting the probabilities of achieving the final state of the process, taking into account the attributes of log events

Time-Aware Probabilistic Knowledge Graphs

The emergence of open information extraction as a tool for constructing and expanding knowledge graphs has aided the growth of temporal data, for instance, YAGO, NELL and Wikidata. While YAGO and Wikidata maintain the valid time of facts, NELL records the time point at which a fact is retrieved from some Web corpora. Collectively, these knowledge graphs (KG) store facts extracted from Wikipedia and other sources. Due to the imprecise nature of the extraction tools that are used to build and expand KG, such as NELL, the facts in the KG are weighted (a confidence value representing the correctness of a fact). Additionally, NELL can be considered as a transaction time KG because every fact is associated with extraction date. On the other hand, YAGO and Wikidata use the valid time model because they maintain facts together with their validity time (temporal scope). In this paper, we propose a bitemporal model (that combines transaction and valid time models) for maintaining and querying bitemporal probabilistic knowledge graphs. We study coalescing and scalability of marginal and MAP inference. Moreover, we show that complexity of reasoning tasks in atemporal probabilistic KG carry over to the bitemporal setting. Finally, we report our evaluation results of the proposed model

Ontology-Mediated Query Answering over Log-Linear Probabilistic Data: Extended Version

Large-scale knowledge bases are at the heart of modern information systems. Their knowledge is inherently uncertain, and hence they are often materialized as probabilistic databases. However, probabilistic database management systems typically lack the capability to incorporate implicit background knowledge and, consequently, fail to capture some intuitive query answers. Ontology-mediated query answering is a popular paradigm for encoding commonsense knowledge, which can provide more complete answers to user queries. We propose a new data model that integrates the paradigm of ontology-mediated query answering with probabilistic databases, employing a log-linear probability model. We compare our approach to existing proposals, and provide supporting computational results

Uniform Reliability of Self-Join-Free Conjunctive Queries

The reliability of a Boolean Conjunctive Query (CQ) over a tuple-independent probabilistic database is the probability that the CQ is satisfied when the tuples of the database are sampled one by one, independently, with their associated probability. For queries without self-joins (repeated relation symbols), the data complexity of this problem is fully characterized in a known dichotomy: reliability can be computed in polynomial time for hierarchical queries, and is #P-hard for non-hierarchical queries. Hierarchical queries also characterize the tractability of queries for other tasks: having read-once lineage formulas, supporting insertion/deletion updates to the database in constant time, and having a tractable computation of tuples\u27 Shapley and Banzhaf values. In this work, we investigate a fundamental counting problem for CQs without self-joins: how many sets of facts from the input database satisfy the query? This is equivalent to the uniform case of the query reliability problem, where the probability of every tuple is required to be 1/2. Of course, for hierarchical queries, uniform reliability is in polynomial time, like the reliability problem. However, it is an open question whether being hierarchical is necessary for the uniform reliability problem to be in polynomial time. In fact, the complexity of the problem has been unknown even for the simplest non-hierarchical CQs without self-joins. We solve this open question by showing that uniform reliability is #P-complete for every non-hierarchical CQ without self-joins. Hence, we establish that being hierarchical also characterizes the tractability of unweighted counting of the satisfying tuple subsets. We also consider the generalization to query reliability where all tuples of the same relation have the same probability, and give preliminary results on the complexity of this problem

Query-Driven On-The-Fly Knowledge Base Construction

Today's openly available knowledge bases, such as DBpedia, Yago, Wikidata or Freebase, capture billions of facts about the world's entities. However, even the largest among these (i) are still limited in up-to-date coverage of what happens in the real world, and (ii) miss out on many relevant predicates that precisely capture the wide variety of relationships among entities. To overcome both of these limitations, we propose a novel approach to build on-the-fly knowledge bases in a query-driven manner. Our system, called QKBfly, supports analysts and journalists as well as question answering on emerging topics, by dynamically acquiring relevant facts as timely and comprehensively as possible. QKBfly is based on a semantic-graph representation of sentences, by which we perform three key IE tasks, namely named-entity disambiguation, co-reference resolution and relation extraction , in a light-weight and integrated manner. In contrast to Open IE, our output is canonicalized. In contrast to traditional IE, we capture more predicates, including ternary and higher-arity ones. Our experiments demonstrate that QKBfly can build high-quality, on-the-fly knowledge bases that can readily be deployed, e.g., for the task of ad-hoc question answering. </jats:p

Uniform Reliability of Self-Join-Free Conjunctive Queries

The reliability of a Boolean Conjunctive Query (CQ) over a tuple-independent probabilistic database is the probability that the CQ is satisfied when the tuples of the database are sampled one by one, independently, with their associated probability. For queries without self-joins (repeated relation symbols), the data complexity of this problem is fully characterized by a known dichotomy: reliability can be computed in polynomial time for hierarchical queries, and is #P-hard for non-hierarchical queries. Inspired by this dichotomy, we investigate a fundamental counting problem for CQs without self-joins: how many sets of facts from the input database satisfy the query? This is equivalent to the uniform case of the query reliability problem, where the probability of every tuple is required to be 1/2. Of course, for hierarchical queries, uniform reliability is solvable in polynomial time, like the reliability problem. We show that being hierarchical is also necessary for this tractability (under conventional complexity assumptions). In fact, we establish a generalization of the dichotomy that covers every restricted case of reliability in which the probabilities of tuples are determined by their relation