1,642 research outputs found
Fuzzy expert systems in civil engineering
Imperial Users onl
Neurosymbolic AI for Reasoning on Graph Structures: A Survey
Neurosymbolic AI is an increasingly active area of research which aims to
combine symbolic reasoning methods with deep learning to generate models with
both high predictive performance and some degree of human-level
comprehensibility. As knowledge graphs are becoming a popular way to represent
heterogeneous and multi-relational data, methods for reasoning on graph
structures have attempted to follow this neurosymbolic paradigm. Traditionally,
such approaches have utilized either rule-based inference or generated
representative numerical embeddings from which patterns could be extracted.
However, several recent studies have attempted to bridge this dichotomy in ways
that facilitate interpretability, maintain performance, and integrate expert
knowledge. Within this article, we survey a breadth of methods that perform
neurosymbolic reasoning tasks on graph structures. To better compare the
various methods, we propose a novel taxonomy by which we can classify them.
Specifically, we propose three major categories: (1) logically-informed
embedding approaches, (2) embedding approaches with logical constraints, and
(3) rule-learning approaches. Alongside the taxonomy, we provide a tabular
overview of the approaches and links to their source code, if available, for
more direct comparison. Finally, we discuss the applications on which these
methods were primarily used and propose several prospective directions toward
which this new field of research could evolve.Comment: 21 pages, 8 figures, 1 table, currently under review. Corresponding
GitHub page here: https://github.com/NeSymGraph
Learning with Graphs using Kernels from Propagated Information
Traditional machine learning approaches are designed to learn from independent vector-valued data points. The assumption that instances are independent, however, is not always true. On the contrary, there are numerous domains where data points are cross-linked, for example social networks, where persons are linked by friendship relations. These relations among data points make traditional machine learning diffcult and often insuffcient. Furthermore, data points themselves can have complex structure, for example molecules or proteins constructed from various bindings of different atoms. Networked and structured data are naturally represented by graphs, and for learning we aimto exploit their structure to improve upon non-graph-based methods. However, graphs encountered in real-world applications often come with rich additional information. This naturally implies many challenges for representation and learning: node information is likely to be incomplete leading to partially labeled graphs, information can be aggregated from multiple sources and can therefore be uncertain, or additional information on nodes and edges can be derived from complex sensor measurements, thus being naturally continuous. Although learning with graphs is an active research area, learning with structured data, substantially modeling structural similarities of graphs, mostly assumes fully labeled graphs of reasonable sizes with discrete and certain node and edge information, and learning with networked data, naturally dealing with missing information and huge graphs, mostly assumes homophily and forgets about structural similarity. To close these gaps, we present a novel paradigm for learning with graphs, that exploits the intermediate results of iterative information propagation schemes on graphs. Originally developed for within-network relational and semi-supervised learning, these propagation schemes have two desirable properties: they capture structural information and they can naturally adapt to the aforementioned issues of real-world graph data. Additionally, information propagation can be efficiently realized by random walks leading to fast, flexible, and scalable feature and kernel computations. Further, by considering intermediate random walk distributions, we can model structural similarity for learning with structured and networked data. We develop several approaches based on this paradigm. In particular, we introduce propagation kernels for learning on the graph level and coinciding walk kernels and Markov logic sets for learning on the node level. Finally, we present two application domains where kernels from propagated information successfully tackle real-world problems
Detecting Irrelevant subtrees to improve probabilistic learning from tree-structured data
International audienceIn front of the large increase of the available amount of structured data (such as XML documents), many algorithms have emerged for dealing with tree-structured data. In this article, we present a probabilistic approach which aims at a posteriori pruning noisy or irrelevant subtrees in a set of trees. The originality of this approach, in comparison with classic data reduction techniques, comes from the fact that only a part of a tree (i.e. a subtree) can be deleted, rather than the whole tree itself. Our method is based on the use of confidence intervals, on a partition of subtrees, computed according to a given probability distribution. We propose an original approach to assess these intervals on tree-structured data and we experimentally show its interest in the presence of noise
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