Abhimanyu Lad

Optimization of association rule mining using improved genetic algorithms

In this paper, the main area of concentration was to optimize the rules generated by association rule mining (a priori method), using genetic algorithms. In general the rule generated by association rule mining technique do not consider the negative occurrences of attributes in them, but by using genetic algorithms (GAs) over these rules the system can predict the rules which contains negative attributes. The main motivation for using GAs in the discovery of high-level prediction rules is that they perform a global search and cope better with attribute interaction than the greedy rule induction algorithms often used in data mining. The improvements applied in GAs are definitely going to help the rule based systems used for classification as described in results and conclusions.

Modeling Expected Utility of Multi-session Information Distillation

An open challenge in information distillation is the evaluation and optimization of the utility of ranked lists with respect to flexible user interactions over multiple sessions. Utility depends on both the relevance and novelty of documents, and the novelty in turn depends on the user interaction history. However, user behavior is non-deterministic. We propose a new probabilistic framework for stochastic modeling of user behavior when browsing multi-session ranked lists, and a novel approximation method for efficient computation of the expected utility over numerous user-interaction patterns. Using this framework, we present the first utility-based evaluation over multi-session search scenarios defined on the TDT4 corpus of news stories, using a state-of-the-art information distillation system. We demonstrate that the distillation system obtains a 56.6% utility enhancement by combining multi-session adaptive filtering with novelty detection and utility-based optimization of system parameters for optimal ranked list lengths.

Generalizing from relevance feedback using named entity wildcards

Traditional adaptive filtering systems learn the users interests in a rather simple way - words from relevant documents are favored in the query model, while words from irrelevant documents are down-weighted. This biases the query model towards specific words seen in the past, causing the system to favor documents containing relevant but redundant information over documents that use previously unseen words to denote new facts about the same news event. This paper proposes news ways of generalizing from relevance feedback by augmenting the traditional bag-of-words query model with named entity wildcards that are anchored in context. The use of wildcards allows generalization beyond specific words, while contextual restrictions limit the wildcard-matching to entities related to the users query. We test our new approach in a nugget-level adaptive filtering system and evaluate it in terms of both relevance and novelty of the presented information. Our results indicate that higher recall is obtained when lexical terms are generalized using wildcards. However, such wildcards must be anchored to their context to maintain good precision. How the context of a wildcard is represented and matched against a given document also plays a crucial role in the performance of the retrieval system.

SpamNet – spam detection using PCA and neural networks

This paper describes SpamNet – a spam detection program, which uses a combination of heuristic rules and mail content analysis to detect and filter out even the most cleverly written spam mails from the users mail box, using a feed-forward neural network. SpamNet is able to adapt itself to changing mail patterns of the user. We demonstrate the power of Principal Component Analysis to improve the performance and efficiency of the spam detection process, and compare it with directly using words as features for classification. Emphasis is laid on the effect of domain specific preprocessing on the error rates of the classifier.

Active Ordering of Interactive Prediction Tasks

Many applications involve a set of prediction tasks that must be accomplished sequentially through user interaction. If the tasks are interdependent, the order in which they are posed may have a significant impact on the effective utilization of user feedback by the prediction systems, affecting their overall performance. This paper presents a novel approach for dynamically ordering a series of prediction tasks by taking into account the effect of user feedback on the performance of multiple prediction systems. The proposed approach represents a general strategy for learning incrementally during test phase when the system interacts with the end-user, who expects good performance instead of merely providing correct labels to the system. Therefore, the system must balance system benefit against user benefit when selecting items for user’s attention. We apply the proposed approach to two practical applications that involve interactive trouble report generation and document annotation, respectively. Our experiments show significant improvements in prediction performance (in terms of Mean Average Precision) using the proposed active ordering approach, as compared to baseline approaches that either determine a task order offline and hold it fixed during test phase, or do not optimize the order at all.

GRAPH STRUCTURE LEARNING FOR TASK ORDERING

In many practical applications, multiple interrelated tasks must be accomplished sequentially through user interaction with retrieval, classification and recommendation systems. The ordering of the tasks may have a significant impact on the overall utility (or performance) of the systems; hence optimal ordering of tasks is desirable. However, manual specification of optimal ordering is often difficult when task dependencies are complex, and exhaustive search for the optimal order is computationally intractable when the number of tasks is large. We propose a novel approach to this problem by using a directed graph to represent partialorder preferences among task pairs, and using link analysis (HITS and PageRank) over the graph as a heuristic to order tasks based on how important they are in reinforcing and propagating the ordering preference. These strategies allow us to find near-optimal solutions with efficient computation, scalable to large applications. We conducted a comparative evaluation of the proposed approach on a form-filling application involving a large collection of business proposals from the Accenture Consulting & Technology Company, using SVM classifiers to recommend keywords, collaborators, customers, technical categories and other related fillers for multiple fields in each proposal. With the proposed approach we obtained nearoptimal task orders that improved the utility of the recommendation system by 27% in macro-averaged F1, and 13% in micro-averaged F1, compared to the results obtained using arbitrarily chosen orders, and that were competitive against the best order suggested by domain experts.