We investigate the notion of classical negation from a non-classical perspective. In particular, one aim is to determine what classical negation amounts to in a paracomplete and paraconsistent four-valued setting. We first give a general semantic characterization of classical negation and then consider an axiomatic expansion BD+ of four-valued Belnap–Dunn logic by classical negation. We show th...

This paper is an attempt to model to what extent an intuitionistic fuzzy set is self-contradictory, both in the case of selfcontradiction regarding a strong intuitionistic negation, and without depending on a specific negation. For this purpose, firstly, a geometrical study on self-contradiction regarding a negation is considered; afterwards some functions to measure degrees of self-contradicto...

OBJECTIVE Automatically identifying findings or diseases described in clinical textual reports requires determining whether clinical observations are present or absent. We evaluate the use of negation phrases and the frequency of negation in free-text clinical reports. METHODS A simple negation algorithm was applied to ten types of clinical reports (n=42,160) dictated during July 2000. We cou...

BACKGROUND Identification of negation in electronic health records is essential if we are to understand the computable meaning of the records: Our objective is to compare the accuracy of an automated mechanism for assignment of Negation to clinical concepts within a compositional expression with Human Assigned Negation. Also to perform a failure analysis to identify the causes of poorly identif...

Entailment detection systems are generally designed to work either on single words, relations or full sentences. We propose a new task – detecting entailment between dependency graph fragments of any type – which relaxes these restrictions and leads to much wider entailment discovery. An unsupervised framework is described that uses intrinsic similarity, multi-level extrinsic similarity and the...

Although negation-free languages are widely used in logic and computer science, relatively little is known about their expressive power. To address this issue we consider a kind of non-symmetric bisimuIations called directed simulations, and use these to analyze the expressive power and model theory of negation-free modal and temporal languages. We first use them to obtain preservation, safety ...

The present research investigated the effects of negation on young and older adults’ comprehension of sentences. Participants read sentences, named probe words, answered comprehension questions, and completed the operation-span test. Negation adversely affected comprehension in both age groups such that probe word naming times were marginally slower and comprehension accuracy was reduced for ne...