21 citations · 64 across the 16 of their papers we have counts for
16 papers
From Time to Space: The Impact of Linearity in Higher-Order Datalog
Angelos Charalambidis, Babis Kostopoulos, Panos Rondogiannis
We consider a fragment of Higher-Order Datalog with negation and argue that it generalizes the familiar and important fragment of Linear Datalog. We investigate the expressive powe…
Equilibrium Semantics and Strong Equivalence for Higher-Order Logic Programs
Angelos Charalambidis, Giannos Chatziagapis, Babis Kostopoulos +1
One of the most significant achievements of equilibrium logic was the characterization of strong equivalence, a property crucial for program transformation and optimization in Answ…
The Power of Negation in Higher-Order Datalog
Angelos Charalambidis, Babis Kostopoulos, Christos Nomikos +1
We investigate the expressive power of Higher-Order Datalog under both the well-founded and the stable model semantics, establishing tight connections with complexity classe…
Dealing with Inconsistency for Reasoning over Knowledge Graphs: A Survey
Anastasios Nentidis, Charilaos Akasiadis, Angelos Charalambidis +1
In Knowledge Graphs (KGs), where the schema of the data is usually defined by particular ontologies, reasoning is a necessity to perform a range of tasks, such as retrieval of info…
Recursive Function Definitions in Static Dataflow Graphs and their Implementation in TensorFlow
Kelly Kostopoulou, Angelos Charalambidis, Panos Rondogiannis
Modern machine learning systems represent their computations as dataflow graphs. The increasingly complex neural network architectures crave for more powerful yet efficient program…
The Stable Model Semantics for Higher-Order Logic Programming
Bart Bogaerts, Angelos Charalambidis, Giannos Chatziagapis +3
We propose a stable model semantics for higher-order logic programs. Our semantics is developed using Approximation Fixpoint Theory (AFT), a powerful formalism that has successfull…
Strong Equivalence of Logic Programs with Ordered Disjunction: a Logical Perspective
Angelos Charalambidis, Christos Nomikos, Panos Rondogiannis
Logic Programs with Ordered Disjunction (LPODs) extend classical logic programs with the capability of expressing preferential disjunctions in the heads of program rules. The initi…
A Logical Characterization of the Preferred Models of Logic Programs with Ordered Disjunction
Angelos Charalambidis, Panos Rondogiannis, Antonis Troumpoukis
Logic Programs with Ordered Disjunction (LPODs) extend classical logic programs with the capability of expressing alternatives with decreasing degrees of preference in the heads of…
Lexicographic Logic: a Many-valued Logic for Preference Representation
Angelos Charalambidis, Giorgos Papadimitriou, Panos Rondogiannis +1
Logical formalisms provide a natural and concise means for specifying and reasoning about preferences. In this paper, we propose lexicographic logic, an extension of classical prop…
The Expressive Power of Higher-Order Datalog
Angelos Charalambidis, Christos Nomikos, Panos Rondogiannis
A classical result in descriptive complexity theory states that Datalog expresses exactly the class of polynomially computable queries on ordered databases. In this paper we extend…
Predicate Specialization for Definitional Higher-order Logic Programs
Antonis Troumpoukis, Angelos Charalambidis
Higher-order logic programming is an interesting extension of traditional logic programming that allows predicates to appear as arguments and variables to be used where predicates…
Approximation Fixpoint Theory and the Well-Founded Semantics of Higher-Order Logic Programs
Angelos Charalambidis, Panos Rondogiannis, Ioanna Symeonidou
We define a novel, extensional, three-valued semantics for higher-order logic programs with negation. The new semantics is based on interpreting the types of the source language as…
An extension of SPARQL for expressing qualitative preferences
Antonis Troumpoukis, Stasinos Konstantopoulos, Angelos Charalambidis
In this paper we present SPREFQL, an extension of the SPARQL language that allows appending a PREFER clause that expresses "soft" preferences over the query results obtained by the…
Equivalence of two Fixed-Point Semantics for Definitional Higher-Order Logic Programs
Angelos Charalambidis, Panos Rondogiannis, Ioanna Symeonidou
Two distinct research approaches have been proposed for assigning a purely extensional semantics to higher-order logic programming. The former approach uses classical domain theore…
Minimum Model Semantics for Extensional Higher-order Logic Programming with Negation
Angelos Charalambidis, Zoltán Ésik, Panos Rondogiannis
Extensional higher-order logic programming has been introduced as a generalization of classical logic programming. An important characteristic of this paradigm is that it preserves…
Extensional Higher-Order Logic Programming
A. Charalambidis, K. Handjopoulos, P. Rondogiannis +1
We propose a purely extensional semantics for higher-order logic programming. In this semantics program predicates denote sets of ordered tuples, and two predicates are equal iff t…