Associative classification is a promising technique to build accurate classifiers. However, in large or correlated data sets, association rule mining may yield huge rule sets. Hence, several pruning techniques have been proposed to select a small subset of high-quality rules. Since the availability of a "rich" rule set may improve the accuracy of the classifier, we argue that rule pruning should be reduced to a minimum. The L³ associative classifier is built by means of a lazy pruning technique that discards exclusively rules that only misclassify training data. The classification of unlabeled data is performed in two steps. A small subset of high-quality rules is first considered. When this set is not able to classify the data, a larger rule set is exploited. This second set includes rules usually discarded by previous approaches. To cope with the need of mining large rule sets and to efficiently use them for classification, a compact form is proposed to represent a complete rule set in a space-efficient way and without information loss. An extensive experimental evaluation on real and synthetic data sets shows that L:i improves the classification accuracy with respect to previous approaches.

Wildfire damage severity census is a crucial activity for estimating monetary losses and for planning a prompt restoration of the affected areas. It consists in assigning, after a wildfire, a numerical damage/severity level, between 0 and 4, to each sub-area of the hit area. While burned area identification has been automatized by means of machine learning algorithms, the wildfire damage severity census operation is usually still performed manually and requires a significant effort of domain experts through the analysis of imagery and, sometimes, on-site missions. In this paper, we propose a novel supervised learning approach for the automatic estimation of the damage/severity level of the hit areas after the wildfire extinction. Specifically, the proposed approach, leveraging on the combination of a classification algorithm and a regression one, predicts the damage/severity level of the sub-areas of the area under analysis by processing a single post-fire satellite acquisition. Our approach has been validated in five different European countries and on 21 wildfires. It has proved to be robust for the application in several geographical contexts presenting similar geological aspects.

Frequent weighted itemsets represent correlations frequently holding in data in which items may weight differently. However, in some contexts, e.g., when the need is to minimize a certain cost function, discovering rare data correlations is more interesting than mining frequent ones. This paper tackles the issue of discovering rare and weighted itemsets, i.e., the infrequent weighted itemset (IWI) mining problem. Two novel quality measures are proposed to drive the IWI mining process. Furthermore, two algorithms that perform IWI and Minimal IWI mining efficiently, driven by the proposed measures, are presented. Experimental results show efficiency and effectiveness of the proposed approach.

Associative classification is a promising technique forthe generation of highly precise classifiers. Previous workspropose several clever techniques to prune the huge set ofgenerated rules, with the twofold aim of selecting a smallset of high quality rules, and reducing the chance of overfitting.In this paper, we argue that pruning should be reducedto a minimum and that the availability of a large rule basemay improve the precision of the classifier, without affectingits performance. In L3 (Live and Let Live), a new algorithmfor associative classification, a lazy pruning technique iterativelydiscards all rules that only yield wrong case classifications.Classification is performed in two steps. Initially, ruleswhich have already correctly classified at least one trainingcase, sorted by confidence, are considered. If the caseis still unclassified, the remaining rules (unused during thetraining phase) are considered, again sorted by confidence.Extensive experiments on 26 databases from the UCImachine learning database repository show that L3 improvesthe classification precision with respect to previousapproaches.

Itemset mining is a well-known exploratory data mining technique used to discover interesting correlations hidden in a data collection. Since it supports different targeted analyses, it is profitably exploited in a wide range of different domains, ranging from network traffic data to medical records. With the increasing amount of generated data, different scalable algorithms have been developed, exploiting the advantages of distributed computing frameworks, such as Apache Hadoop and Spark. This paper reviews Hadoop- and Spark-based scalable algorithms addressing the frequent itemset mining problem in the Big Data domain through both theoretical and experimental comparative analyses. Since the itemset mining task is computationally expensive, its distribution and parallelization strategies heavily affect memory usage, load balancing, and communication costs. A detailed discussion of the algorithmic choices of the distributed methods for frequent itemset mining is followed by an experimental analysis comparing the performance of state-of-the-art distributed implementations on both synthetic and real datasets. The strengths and weaknesses of the algorithms are thoroughly discussed with respect to the dataset features (e.g., data distribution, average transaction length, number of records), and specific parameter settings. Finally, based on theoretical and experimental analyses, open research directions for the parallelization of the itemset mining problem are presented