8 research outputs found
Semantic Inference on Heterogeneous E-Marketplace Activities
An electronic marketplace (e-marketplace) is a common business information space populated with many entities of different system types. Each of them has its own context of how to process activities. This leads to heterogeneous e-marketplace activities, which are difficult to make interoperable and inferred from one entity to another. This study solves this problem by proposing a concept of separation strategy and implementing it through providing a semantic inference engine with a novel inference algorithm. The solution, called the RuleXPM approach, enables one to semantically infer a next e-marketplace activity across multiple contexts/domains. Experiments show that the cross-context/cross-domain semantic inference is achievable. This paper is an understanding of many aspects related to heterogeneous activity inference
Fast subsumption checks using anti-links
The concept of "anti-link" is defined, and useful
equivalence-preserving operations based on anti-links are
introduced.These operations eliminate a potentially large number
of subsumed paths in a negation normal form formula.Those
anti-links that directly indicate the presence of subsumed paths
are characterized. The operations have linear time complexity in
the size of that part of the formula containing the anti-link.
The problem of removing all subsumed paths in an NNF formula is
shown to be NP-hard, even though such formulas may be small
relative to the size of their path sets. The general problem of
determining whether there exists a pair of subsumed paths
associated with an arbitrary anti-link is shown to be NP-complete.
Additional techniques based on "strictly pure full blocks" are
introduced and are also shown to eliminate redundant subsumption
checks. The effectiveness of these techniques is examined with
respect to some benchmark examples from the literature
Algorithms for computational argumentation in artificial intelligence
Argumentation is a vital aspect of intelligent behaviour by humans. It provides the means for comparing
information by analysing pros and cons when trying to make a decision. Formalising argumentation in
computational environment has become a topic of increasing interest in artificial intelligence research
over the last decade.
Computational argumentation involves reasoning with uncertainty by making use of logic in order
to formalize the presentation of arguments and counterarguments and deal with conflicting information.
A common assumption for logic-based argumentation is that an argument is a pair where Φ is
a consistent set which is minimal for entailing a claim α. Different logics provide different definitions
for consistency and entailment and hence give different options for formalising arguments and counterarguments.
The expressivity of classical propositional logic allows for complicated knowledge to be
represented but its computational cost is an issue. This thesis is based on monological argumentation
using classical propositional logic [12] and aims in developing algorithms that are viable despite the
computational cost. The proposed solution adapts well established techniques for automated theorem
proving, based on resolution and connection graphs. A connection graph is a graph where each node is
a clause and each arc denotes there exist complementary disjuncts between nodes. A connection graph
allows for a substantially reduced search space to be used when seeking all the arguments for a claim
from a given knowledgebase. In addition, its structure provides information on how its nodes can be linked
with each other by resolution, providing this way the basis for applying algorithms which search for
arguments by traversing the graph. The correctness of this approach is supported by theoretical results,
while experimental evaluation demonstrates the viability of the algorithms developed. In addition, an
extension of the theoretical work for propositional logic to first-order logic is introduced
Hierarchical contextual reasoning
Computer supported development of proofs requires user interaction even for theorems that are simple by human standards. In this thesis we define a communication infrastructure as a mediator between the user and the automatic reasoning procedures. It is based on a new uniform meta proof theory for contextual reasoning and encompasses most aspects of communication from the presentation of the proof state, via the supply of relevant contextual information about possible proof continuations, to the support for a hierarchical proof development. The proof theory is uniform for a variety of logics. It exploits proof theoretic annotations in formulas for a contextual reasoning style that is as far as possible intuitive for the user while at the same time still adequate for automatic reasoning procedures. Furthermore, concepts are defined to accomodate both the use and the explicit representation of hierarchies that are inherent in problem solving in general.Das computergestuetzte Beweisen von Theoremen erfordert den Eingriff des menschlichen Benutzers selbst fuer nach menschlichen Maßstaeben einfache Theoreme. Diese Arbeit definiert eine Kommunikationsplattform, die eine synergetische Kooperationsform des Benutzers mit dem Beweisverfahren ermöglicht