Sequential pattern mining, it is not just important in data mining field, but it is the basis of many applications. However, running applications cost time and memory, especially when dealing with dense of the dataset. Setting the proper minimum support threshold is one of the factors that consume more memory and time. However, it is difficult for users to get the appropriate patterns; it may p...

Ranked lists have become a fundamental tool to represent the most important items taken from a large collection of data. Search engines, sports leagues and e-commerce platforms present their results, most successful teams and most popular items in a concise and structured way by making use of ranked lists. This paper introduces the PALEO-J framework which is able to reconstruct top-k database q...

Let D be a collection of D documents, which are strings over an alphabet of size σ, of total length n. We describe a data structure that uses linear space and and reports k most relevant documents that contain a query pattern P , which is a string of length p packed in p/ logσ n words, in time O(p/ logσ n+k). This is optimal in the RAM model in the general case where logD = Θ(log n), and involv...

In a data streaming model, a data owner releases records or documents to a set of users with matching interests, in such a way that the match in interest can be calculated from the correlation between each pair of document and user query. For scalability and availability reasons, this calculation is delegated to third-party servers, which gives rise to the need to protect the integrity and priv...

Preference queries have been largely studied for relational systems but few proposals exist for stream data systems. Most of the existing proposals concern the skyline, top-k or top-k dominating queries, coupled with the sliding-window operator. However, user preferences queries on data streams may be more sophisticated than simple skyline or top-k and may involve more expressive operations on ...

We propose and study a new type of facility location selection query, the top-k most influential location selection query. Given a set M of customers and a set F of existing facilities, this query finds k locations from a set C of candidate locations with the largest influence values, where the influence of a candidate location c (c ∈ C) is defined as the number of customers in M who are the re...

Advances in web technology have given rise to new information retrieval applications. In this paper, we present a model for geographical region search and call this class of query similar region query. Given a spatial map and a query region, a similar region search aims to find the top-k most similar regions to the query region on the spatial map. We design a quadtree based algorithm to access ...

Top-k dominating queries combine the advantages of top-k queries and skyline queries, and eliminate their disadvantages. They return k objects with the highest domination score, which is defined as the number of dominated objects. As a top-k query, the user can bound the number of returned results through the parameter k, and like a skyline query a user-selected scoring function is not required...

We present a data structure for the following problem: Given a tree T , with each of its nodes assigned a color in a totally ordered set, preprocess T to efficiently answer queries for the top k distinct colors on the path between two nodes, reporting the colors sorted in descending order. Our data structure requires linear space of O(n) words and answers queries in O(k) time.

The research on optimization of top-k SPARQL query would largely benefit from the establishment of a benchmark that allows comparing different approaches. For such a benchmark to be meaningful, at least two requirements should hold: 1) the benchmark should resemble reality as much as possible, and 2) it should stress the features of the topk SPARQL queries both from a syntactic and performance ...