An Ontology-Based Recommender System with an Application to the Star Trek Television Franchise

Collaborative filtering based recommender systems have proven to be extremely successful in settings where user preference data on items is abundant. However, collaborative filtering algorithms are hindered by their weakness against the item cold-start problem and general lack of interpretability. Ontology-based recommender systems exploit hierarchical organizations of users and items to enhance browsing, recommendation, and profile construction. While ontology-based approaches address the shortcomings of their collaborative filtering counterparts, ontological organizations of items can be difficult to obtain for items that mostly belong to the same category (e.g., television series episodes). In this paper, we present an ontology-based recommender system that integrates the knowledge represented in a large ontology of literary themes to produce fiction content recommendations. The main novelty of this work is an ontology-based method for computing similarities between items and its integration with the classical Item-KNN (K-nearest neighbors) algorithm. As a study case, we evaluated the proposed method against other approaches by performing the classical rating prediction task on a collection of Star Trek television series episodes in an item cold-start scenario. This transverse evaluation provides insights into the utility of different information resources and methods for the initial stages of recommender system development. We found our proposed method to be a convenient alternative to collaborative filtering approaches for collections of mostly similar items, particularly when other content-based approaches are not applicable or otherwise unavailable. Aside from the new methods, this paper contributes a testbed for future research and an online framework to collaboratively extend the ontology of literary themes to cover other narrative content.Comment: 25 pages, 6 figures, 5 tables, minor revision

Memory without content? Radical enactivism and (post)causal theories of memory

Radical enactivism, an increasingly influential approach to cognition in general, has recently been applied to memory in particular, with Hutto and Peeters New directions in the philosophy of memory, Routledge, New York, 2018) providing the first systematic discussion of the implications of the approach for mainstream philosophical theories of memory. Hutto and Peeters argue that radical enactivism, which entails a conception of memory traces as contentless, is fundamentally at odds with current causal and postcausal theories, which remain committed to a conception of traces as contentful: on their view, if radical enactivism is right, then the relevant theories are wrong. Partisans of the theories in question might respond to Hutto and Peeters’ argument in two ways. First, they might challenge radical enactivism itself. Second, they might challenge the conditional claim that, if radical enactivism is right, then their theories are wrong. In this paper, we develop the latter response, arguing that, appearances to the contrary notwithstanding, radical enactivism in fact aligns neatly with an emerging tendency in the philosophy of memory: radical enactivists and causal and postcausal theorists of memory have begun to converge, for distinct but compatible reasons, on a contentless conception of memory traces

Exploiting extensible background knowledge for clustering-based automatic keyphrase extraction

Keyphrases are single- or multi-word phrases that are used to describe the essential content of a document. Utilizing an external knowledge source such as WordNet is often used in keyphrase extraction methods to obtain relation information about terms and thus improves the result, but the drawback is that a sole knowledge source is often limited. This problem is identified as the coverage limitation problem. In this paper, we introduce SemCluster, a clustering-based unsupervised keyphrase extraction method that addresses the coverage limitation problem by using an extensible approach that integrates an internal ontology (i.e., WordNet) with other knowledge sources to gain a wider background knowledge. SemCluster is evaluated against three unsupervised methods, TextRank, ExpandRank, and KeyCluster, and under the F1-measure metric. The evaluation results demonstrate that SemCluster has better accuracy and computational efficiency and is more robust when dealing with documents from different domains

The effects of mindfulness-based cognitive therapy on affective memory recall dynamics in depression:A mechanistic model of rumination

Objectives: converging research suggests that mindfulness training exerts its therapeutic effects on depression by reducing rumination. Theoretically, rumination is a multifaceted construct that aggregates multiple neurocognitive aspects of depression, including poor executive control, negative and overgeneral memory bias, and persistence or stickiness of negative mind states. Current measures of rumination, most-often self-reports, do not capture these different aspects of ruminative tendencies, and therefore are limited in providing detailed information about the mechanisms of mindfulness. Methods: we developed new insight into the potential mechanisms of rumination, based on three model-based metrics of free recall dynamics. These three measures reflect the patterns of memory retrieval of valenced information: the probability of first recall (Pstart) which represents initial affective bias, the probability of staying with the same valence category rather than switching, which indicates strength of positive or negative association networks (Pstay), and probability of stopping (Pstop) or ending recall within a given valence, which indicates persistence or stickiness of a mind state. We investigated the effects of Mindfulness-Based Cognitive Therapy (MBCT; N = 29) vs. wait-list control (N = 23) on these recall dynamics in a randomized controlled trial in individuals with recurrent depression. Participants completed a standard laboratory stressor, the Trier Social Stress Test, to induce negative mood and activate ruminative tendencies. Following that, participants completed a free recall task consisting of three word lists. This assessment was conducted both before and after treatment or wait-list. Results: while MBCT participant’s Pstart remained relatively stable, controls showed multiple indications of depression-related deterioration toward more negative and less positive bias. Following the intervention, MBCT participants decreased in their tendency to sustain trains of negative words and increased their tendency to sustain trains of positive words. Conversely, controls showed the opposite tendency: controls stayed in trains of negative words for longer, and stayed in trains of positive words for less time relative to pre-intervention scores. MBCT participants tended to stop recall less often with negative words, which indicates less persistence or stickiness of negatively valenced mental context. Conclusion: MBCT participants showed a decrease in patterns that may perpetuate rumination on all three types of recall dynamics (Pstart, Pstay, and Pstop), compared to controls. MBCT may weaken the strength of self-perpetuating negative associations networks that are responsible for the persistent and “sticky” negative mind states observed in depression, and increase the positive associations that are lacking in depression. This study also offers a novel, objective method of measuring several indices of ruminative tendencies indicative of the underlying mechanisms of rumination

Collaborative design of educational digital libraries for African higher education

This thesis will develop a model that can be used to guide collaborative design of educational digital libraries that are relevant to the learning objectives and are appropriate to African Higher Education. Factors affecting connections between educational digital library capabilities, learning processes and learners’ needs in higher education will be identified and used to develop the model. These factors will be identified through qualitative studies with the key players (i.e. academics, information professionals, digital library technical designers and students). The model will be iteratively developed and later evaluated for correctness by some of the key players. So far a preliminary literature review has been done to locate related work and identify knowledge gaps. In addition, a pilot study has been carried out and identified some temporal factors that will be pursued further in the proposed study

ImpacT2 project: preliminary study 1: establishing the relationship between networked technology and attainment

This report explored teaching practices, beliefs and teaching styles and their influences on ICT use and implementation by pupils. Additional factors explored included the value of school and LEA policies and teacher competence in the use of ICT in classroom settings. ImpaCT2 was a major longitudinal study (1999-2002) involving 60 schools in England, its aims were to: identify the impact of networked technologies on the school and out-of-school environment; determine whether or not this impact affected the educational attainment of pupils aged 816 years (at Key Stages 2, 3, and 4); and provide information that would assist in the formation of national, local and school policies on the deployment of IC

Remarks on deixis

The prevailing conception of deixis is oriented to the idea of 'concrete' physical and perceptual characteristics of the situation of speech. Signs standardly adduced as typical deictics are I, you, here, now, this, that. I and you are defined as meaning "the person producing the utterance in question" and "the person spoken to", here and now as meaning "where the speaker is at utterance time" and "at the moment the utterance is made" (also, "at the place/time of the speech exchange"); similarly, the meanings of this and that are as a rule defined via proximity to speaker's physical location. The elements used in such definitions form the conceptual framework of most of the general characterisations of deixis in the literature. [...] There is much in the literature, of course, that goes far beyond this framework . A great variety of elements, mostly with very abstract meanings, have been found to share deictic characteristics although they do not fit into the personnel-place-time-of-utterance schema. The adequacy of that schema is also called into question by many observations to the effect that the use of such standard deictics as here, now, this, that cannot really be accounted for on its basis, and by the far-reaching possibilities of orienting deictics to reference points in situations other than the situation of speech, to 'deictic centers' other than the speaker. [...] Analyses along the lines of the standard conception regularly acknowledge the existence of deviations from the assumed basic meanings. One traditional solution attributes them to speaker's "subjectivity", or to differences between "physical" and "psychological" space or time; in a similar vein, metaphorical extensions may be said to be at play, or a distinction between prototypical and non-prototypical meanings invoked. Quite apart from the question of the relative merits of these explanatory principles, which I do not wish to discuss here, the problem with all such accounts is that the definitions of the assumed basic meanings themselves are founded on axiom rather than analysis of situated use. The logical alternative, of course, is to set out for more abstract and comprehensive meaning definitions from the start. In fact, a number of recent, discourse-oriented, treatments of the demonstratives proceed this way; they view those elements as processing instructions rather than signs with inherently spatial denotation (Isard 1975, Hawkins 1978, Kirsner 1979, Linde 1979 , Ehlich 1982.

Tracking the associative boost in infancy.

Do words that are both associatively and taxonomically related prime each other in the infant mental lexicon? We explore the impact of these semantic relations in the emerging lexicon. Using the head-turn preference procedure, we show that 18-month-old infants have begun to construct a semantic network of associatively and taxonomically related words, such as dog-cat or apple-cheese. We demonstrate that priming between words is longer-lasting when the relationship is both taxonomic and associative, as opposed to purely taxonomic, reflecting the associative boost reported in the adult priming literature. Our results demonstrate that 18-month-old infants are able to construct a lexical-semantic network based on associative and taxonomic relations between words in the network, and that lexical-semantic links are more robust when they are both associative and taxonomic in character. Furthermore, the manner in which activation is propagated through the emerging lexical-semantic network appears to depend upon the type of semantic relation between words. We argue that 18-month-old infants have a mental lexicon that shares important structural and processing properties with that of the adult system

Goldilocks Forgetting in Cross-Situational Learning

Given that there is referential uncertainty (noise) when learning words, to what extent can forgetting filter some of that noise out, and be an aid to learning? Using a Cross Situational Learning model we find a U-shaped function of errors indicative of a "Goldilocks" zone of forgetting: an optimum store-loss ratio that is neither too aggressive nor too weak, but just the right amount to produce better learning outcomes. Forgetting acts as a high-pass filter that actively deletes (part of) the referential ambiguity noise, retains intended referents, and effectively amplifies the signal. The model achieves this performance without incorporating any specific cognitive biases of the type proposed in the constraints and principles account, and without any prescribed developmental changes in the underlying learning mechanism. Instead we interpret the model performance as more of a by-product of exposure to input, where the associative strengths in the lexicon grow as a function of linguistic experience in combination with memory limitations. The result adds a mechanistic explanation for the experimental evidence on spaced learning and, more generally, advocates integrating domain-general aspects of cognition, such as memory, into the language acquisition process