International audience

We propose to tackle dynamic texture video classification as a pattern mining problem. In a nutshell, videos are represented by frequent sequences of representative patches. Firstly, we use a Gaussian Mixture Model to make the clustering of patches from training videos. Secondly, a soft assignment is used as an encoding method to construct sequences of probability vectors (p-sequences) representing sequences of spatio-temporal patches. Thirdly, for each class, we mine meaningful motifs appearing inside the training p-sequences by means of an adapted data mining approach. Finally, feature vectors are constructed from the mined motifs, using the probabilistic support, which quantifies the match between the p-sequences, of the video to be classified, and the key-motifs of the classes. Experimental results and analysis for dynamic texture classification on benchmark datasets (i.e. UCLA, Traffic) show the interest of the proposed method.

International audience

In recent years, the field of pattern mining has shifted to user-centered methods. In such a context, it is necessary to have a tight coupling between the system and the user where mining techniques provide results at any time or within a short response time of only few seconds. Pattern sampling is a non-exhaustive method for instantly discovering relevant patterns that ensures a good interactivity while providing strong statistical guarantees due to its random nature. Curiously, such an approach investigated for itemsets and subgraphs has not yet been applied to sequential patterns, which are useful for a wide range of mining tasks and application fields. In this paper, we propose the first method for sequential pattern sampling. In addition to address sequential data, the originality of our approach is to introduce a constraint on the norm to control the length of the drawn patterns and to avoid the pitfall of the "long tail" where the rarest patterns flood the user. We propose a new constrained two-step random procedure, named CSSampling, that randomly draws sequential patterns according to frequency with an interval constraint on the norm. We demonstrate that this method performs an exact sampling. Moreover, despite the use of rejection sampling, the experimental study shows that CSSampling remains efficient and the constraint helps to draw general patterns of the "head". We also illustrate how to benefit from these sampled patterns to instantly build an associative classifier dedicated to sequences. This classification approach rivals state of the art proposals showing the interest of constrained sequential pattern sampling.

Sentiment classification in text documents is an active data mining research topic in opinion retrieval and analysis. Different from previous studies concentrating on the development of effective classifiers, in this paper, we focus on the extraction

Sequential pattern mining is the method that has received much attention in sequence data mining research and applications, however, a drawback is that it does not profit from prior knowledge of domains. In our previous work, we proposed a belief-driven method with fuzzy set theory for discovering the unexpected sequences that contradict existing knowledge of data, including occurrence constraints and semantic contradictions. In this paper, we present a new approach that discovers unexpected sequences with determining semantic contradictions by using concept hierarchies associated with the data. We evaluate the effectiveness of our approach with experiments on Web usage analysis.

The transversal hypergraph enumeration based algorithms can be efficient in mining frequent itemsets, however it is difficult to apply them to sequence mining problems. In this paper we first analyze the constraints of using transversal hypergraph enumeration in itemset mining, then propose the ordered pattern model for representing and mining sequences with respect to these constraints. We show that the problem of mining sequential patterns can be transformed to the problem of mining frequent ordered patterns, and therefore we propose an application of the Dualize and Advance algorithm, which is transversal hypergraph enumeration based, in mining sequential patterns.