Query languages for graph databases started to be investigated some 25 years ago. With much current data, such as linked data on the Web and social network being graph-structured, there has been a recent resurgence in interest query languages. We provide brief survey of many that have proposed, focussing core functionality provided these also consider issues expressive power computational complexity evaluation.

We consider the following problem: given a labelled directed graph G and regular expression R, find all pairs of nodes connected by simple path such that concatenation labels along satisfies R. The problem is motivated observation many recursive queries in relational databases can be expressed this form, implementation query language, $\textbf{G}^{+}$, based on observation. show general intractable, but present an algorithm than runs polynomial time size when are free conflicts. also class...

We define a language G for querying data represented as labeled graph G. By considering relation, this graphical query can be viewed relational language, and its expressive power compared to that of other languages. do not propose an alternative general purpose languages, but rather complementary in which recursive queries are simple formulate. The user is aided formulation by means interface. provision regular expressions allows more than transitive closure posed, although the powerful...

For many problems arising in the setting of graph querying (such as finding semantic associations RDF graphs, exact and approximate pattern matching, sequence alignment, etc.), power standard languages such widely studied conjunctive regular path queries (CRPQs) is insufficient at least two ways. First, they cannot output paths second, more crucially, express relationships among paths. We thus propose a class extended CRPQs, called ECRPQs, which add relations on tuples paths, allow variables...

Classical recommender systems provide users with a list of recommendations where each recommendation consists single item, e.g., book or DVD. However, several applications can benefit from system capable recommending packages items, in the form sets. Sample include travel planning limited budget (price time) and twitter wanting to select worthwhile tweeters follow given that they deal only bounded number tweets. In these contexts, there is need for recommend top-k user choose from.

XML repositories are now a widespread means for storing and exchanging information on the Web. As these become increasingly used in dynamic applications such as e-commerce, there is rapidly growing need mechanism to incorporate reactive functionality an setting. Event-condition-action (ECA) rules technology from active databases natural method supporting suchfunctionality. ECA can be activities automatically enforcing document constraints, maintaining repository statistics, facilitating...

The OWL 2 QL profile of the Web Ontology Language, based on family description logics called DL-Lite, is designed so that data stored in a standard relational database system (RDBMS) can be queried through an ontology via rewriting mechanism, i.e., by query into SQL then answered RDBMS system, without any changes to data. In this paper we propose language whose expressive power goes beyond DL-Lite while still allowing answering queries unions conjunctive two-way regular path (UC2RPQs)...

We define a language G for querying data represented as labeled graph . By considering relation, this graphical query can be viewed relational language, and its expressive power compared to that of other languages. do not propose an alternative general purpose languages, but rather complementary in which recursive queries are simple formulate. The user is aided formulation by means interface. provision regular expressions allows more than transitive closure posed, although the powerful those...

For many problems arising in the setting of graph querying (such as finding semantic associations RDF graphs, exact and approximate pattern matching, sequence alignment, etc.), power standard languages such widely studied conjunctive regular path queries (CRPQs) is insufficient at least two ways. First, they cannot output paths second, more crucially, express relations among paths.

Classical recommender systems provide users with a list of recommendations where each recommendation consists single item, e.g., book or DVD. However, applications such as travel planning can benefit from system capable recommending packages items, under user-specified budget and in the form sets sequences. In this context, there is need for that recommend top-k user to choose from. paper, we propose novel system, CompRec-Trip, which automatically generate composite planning. The leverages...

There are several applications, such as play lists of songs or movies, and shopping carts, where users interested in finding top- k packages, consisting sets items. In response to this need, there has been a recent flurry activity around extending classical recommender systems (RS), which effective at recommending individual items, recommend The few proposals for package RS suffer from one the following drawbacks: they either rely on hard constraints may be difficult specified exactly by...

Top-k query processing has recently received a significant amount of attention due to its wide application in information retrieval, multimedia search and recommendation generation. In this work, we consider the problem how efficiently answer top-k by using previously cached results. While there been some previous work on problem, existing algorithms suffer from either limited scope or lack scalability. paper, propose two novel for handling problem. The first algorithm LPTA+ provides...