516 research outputs found
DESQ: Frequent Sequence Mining with Subsequence Constraints
Frequent sequence mining methods often make use of constraints to control
which subsequences should be mined. A variety of such subsequence constraints
has been studied in the literature, including length, gap, span,
regular-expression, and hierarchy constraints. In this paper, we show that many
subsequence constraints---including and beyond those considered in the
literature---can be unified in a single framework. A unified treatment allows
researchers to study jointly many types of subsequence constraints (instead of
each one individually) and helps to improve usability of pattern mining systems
for practitioners. In more detail, we propose a set of simple and intuitive
"pattern expressions" to describe subsequence constraints and explore
algorithms for efficiently mining frequent subsequences under such general
constraints. Our algorithms translate pattern expressions to compressed finite
state transducers, which we use as computational model, and simulate these
transducers in a way suitable for frequent sequence mining. Our experimental
study on real-world datasets indicates that our algorithms---although more
general---are competitive to existing state-of-the-art algorithms.Comment: Long version of the paper accepted at the IEEE ICDM 2016 conferenc
Constraint-based Sequential Pattern Mining with Decision Diagrams
Constrained sequential pattern mining aims at identifying frequent patterns
on a sequential database of items while observing constraints defined over the
item attributes. We introduce novel techniques for constraint-based sequential
pattern mining that rely on a multi-valued decision diagram representation of
the database. Specifically, our representation can accommodate multiple item
attributes and various constraint types, including a number of non-monotone
constraints. To evaluate the applicability of our approach, we develop an
MDD-based prefix-projection algorithm and compare its performance against a
typical generate-and-check variant, as well as a state-of-the-art
constraint-based sequential pattern mining algorithm. Results show that our
approach is competitive with or superior to these other methods in terms of
scalability and efficiency.Comment: AAAI201
Closing the gap: Sequence mining at scale
Frequent sequence mining is one of the fundamental building blocks in data mining. While the problem has been extensively studied, few of the available techniques are sufficiently scalable to handle datasets with billions of sequences; such large-scale datasets arise, for instance, in text mining and session analysis. In this article, we propose MG-FSM, a scalable algorithm for frequent sequence mining on MapReduce. MG-FSM can handle so-called “gap constraints”, which can be used to limit the output to a controlled set of frequent sequences. Both positional and temporal gap constraints, as well as appropriate maximality and closedness constraints, are supported. At its heart, MG-FSM partitions the input database in a way that allows us to mine each partition independently using any existing frequent sequence mining algorithm. We introduce the notion of ω-equivalency, which is a generalization of the notion of a “projected database” used by many frequent pattern mining algorithms. We also present a number of optimization techniques that minimize partition size, and therefore computational and communication costs, while still maintaining correctness. Our experimental study in the contexts of text mining and session analysis suggests that MG-FSM is significantly more efficient and scalable than alternative approaches
Deep learning for time series classification: a review
Time Series Classification (TSC) is an important and challenging problem in
data mining. With the increase of time series data availability, hundreds of
TSC algorithms have been proposed. Among these methods, only a few have
considered Deep Neural Networks (DNNs) to perform this task. This is surprising
as deep learning has seen very successful applications in the last years. DNNs
have indeed revolutionized the field of computer vision especially with the
advent of novel deeper architectures such as Residual and Convolutional Neural
Networks. Apart from images, sequential data such as text and audio can also be
processed with DNNs to reach state-of-the-art performance for document
classification and speech recognition. In this article, we study the current
state-of-the-art performance of deep learning algorithms for TSC by presenting
an empirical study of the most recent DNN architectures for TSC. We give an
overview of the most successful deep learning applications in various time
series domains under a unified taxonomy of DNNs for TSC. We also provide an
open source deep learning framework to the TSC community where we implemented
each of the compared approaches and evaluated them on a univariate TSC
benchmark (the UCR/UEA archive) and 12 multivariate time series datasets. By
training 8,730 deep learning models on 97 time series datasets, we propose the
most exhaustive study of DNNs for TSC to date.Comment: Accepted at Data Mining and Knowledge Discover
Longest Common Subsequence with Gap Constraints
We consider the longest common subsequence problem in the context of
subsequences with gap constraints. In particular, following Day et al. 2022, we
consider the setting when the distance (i. e., the gap) between two consecutive
symbols of the subsequence has to be between a lower and an upper bound (which
may depend on the position of those symbols in the subsequence or on the
symbols bordering the gap) as well as the case where the entire subsequence is
found in a bounded range (defined by a single upper bound), considered by
Kosche et al. 2022. In all these cases, we present effcient algorithms for
determining the length of the longest common constrained subsequence between
two given strings
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