Search Results for author: Georg Gottlob

Found 13 papers, 4 papers with code

Non-Uniformly Terminating Chase: Size and Complexity

no code implementations22 Apr 2022 Marco Calautti, Georg Gottlob, Andreas Pieris

In this context, a key problem is non-uniform chase termination: does the chase of a database w. r. t.

On the Complexity of Inductively Learning Guarded Rules

no code implementations7 Oct 2021 Andrei Draghici, Georg Gottlob, Matthias Lanzinger

We investigate the computational complexity of mining guarded clauses from clausal datasets through the framework of inductive logic programming (ILP).

Inductive logic programming

The HyperTrac Project: Recent Progress and Future Research Directions on Hypergraph Decompositions

no code implementations29 Dec 2020 Georg Gottlob, Matthias Lanzinger, Davide Mario Longo, Cem Okulmus, Reinhard Pichler

Constraint Satisfaction Problems (CSPs) play a central role in many applications in Artificial Intelligence and Operations Research.

HyperBench: A Benchmark and Tool for Hypergraphs and Empirical Findings

1 code implementation2 Sep 2020 Wolfgang Fischl, Georg Gottlob, Davide Mario Longo, Reinhard Pichler

To cope with the intractability of answering Conjunctive Queries (CQs) and solving Constraint Satisfaction Problems (CSPs), several notions of hypergraph decompositions have been proposed -- giving rise to different notions of width, noticeably, plain, generalized, and fractional hypertree width (hw, ghw, and fhw).

HyperBench: A Benchmark and Tool for Hypergraphs and Empirical Findings

1 code implementation20 Nov 2018 Wolfgang Fischl, Georg Gottlob, Davide M. Longo, Reinhard Pichler

To cope with the intractability of answering Conjunctive Queries (CQs) and solving Constraint Satisfaction Problems (CSPs), several notions of hypergraph decompositions have been proposed -- giving rise to different notions of width, noticeably, plain, generalized, and fractional hypertree width (hw, ghw, and fhw).

Databases

The Space-Efficient Core of Vadalog

no code implementations16 Sep 2018 Gerald Berger, Georg Gottlob, Andreas Pieris, Emanuel Sallinger

Vadalog is a system for performing complex reasoning tasks such as those required in advanced knowledge graphs.

Knowledge Graphs

The Vadalog System: Datalog-based Reasoning for Knowledge Graphs

no code implementations23 Jul 2018 Luigi Bellomarini, Georg Gottlob, Emanuel Sallinger

Yet, Datalog-based reasoning in the presence of existential quantification is in general undecidable.

Knowledge Graphs

Data Science with Vadalog: Bridging Machine Learning and Reasoning

no code implementations23 Jul 2018 Luigi Bellomarini, Ruslan R. Fayzrakhmanov, Georg Gottlob, Andrey Kravchenko, Eleonora Laurenza, Yavor Nenov, Stephane Reissfelder, Emanuel Sallinger, Evgeny Sherkhonov, Lianlong Wu

Following the recent successful examples of large technology companies, many modern enterprises seek to build knowledge graphs to provide a unified view of corporate knowledge and to draw deep insights using machine learning and logical reasoning.

Knowledge Graphs

Datalog: Bag Semantics via Set Semantics

no code implementations17 Mar 2018 Leopoldo Bertossi, Georg Gottlob, Reinhard Pichler

This use of Datalog$^\pm$ is extended to give a set semantics to duplicates in Datalog$^\pm$ itself.

Translation

Tree Projections and Constraint Optimization Problems: Fixed-Parameter Tractability and Parallel Algorithms

no code implementations14 Nov 2017 Georg Gottlob, Gianlugi Greco, Francesco Scarcello

Solution methods have therefore been proposed in the literature that do not require a tree projection to be given, and that either correctly decide whether the given CSP instance is satisfiable, or return that a tree projection actually does not exist.

General and Fractional Hypertree Decompositions: Hard and Easy Cases

2 code implementations3 Nov 2016 Wolfgang Fischl, Georg Gottlob, Reinhard Pichler

It is known that hw(H) <= k can be checked in polynomial time for fixed k, while checking ghw(H) <= k is NP-complete for any k greater than or equal to 3.

Databases Computational Complexity

Deciding Monotone Duality and Identifying Frequent Itemsets in Quadratic Logspace

no code implementations9 Dec 2012 Georg Gottlob

The monotone duality problem is defined as follows: Given two monotone formulas f and g in iredundant DNF, decide whether f and g are dual.

Problem Decomposition

A Backtracking-Based Algorithm for Computing Hypertree-Decompositions

1 code implementation14 Jan 2007 Georg Gottlob, Marko Samer

Hypertree decompositions of hypergraphs are a generalization of tree decompositions of graphs.

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