Keyword search over relational and XML data has grown in popularity since the advent of Web search engines. Keyword search over relational data is significantly different from web search as the required information is often split across multiple tables as a result of normalization. The algorithms and techniques that are applied to databases, thus produce answer trees from the data graph as oppo...

Keyword search on graph structured data has attracted a lot of attention in recent years. Graphs are a natural “lowest common denominator” representation which can combine relational, XML and HTML data. Responses to keyword queries are usually modeled as trees that connect nodes matching the keywords. In this paper we address the problem of keyword search on graphs that may be significantly lar...

Search as a Service (SaaS) is a cloud service model whose main focus is on enterprise search or site-specific web search. Modern companies require fast and accurate information from their internal databases, internal document stores, or through the content of a website. Having a reliable searching mechanism is essential for both internal company staff and for external customers. In this paper t...

Even though a large number of I/O-efficient graph algorithms have been developed, a number of fundamental problems still remain open. For example, no spaceand I/O-efficient algorithms are known for depth-first search or breath-first search in sparse graphs. In this paper, we present two new results on I/O-efficient depth-first search in an important class of sparse graphs, namely undirected emb...

In this paper we refine external exploration for explicit state model checking by a fusion with internal bitstate hashing. External A* provides a method to cope up with large state spaces by efficiently utilizing secondary storage devices like harddisk to maintain the open and closed lists. Duplicates are removed by a two-level refinement scheme that involves sorting a subset of the open list e...

This thesis provides both experimental and theoretical contributions regarding externalmemory dynamic search trees with fast insertions. The first contribution is the implementation of the buffered repository B-tree, a data structure that provably outperforms B-trees for updates at the cost of a constant factor decrease in query performance. This thesis also describes the cache-oblivious lookah...

Recent research on external-memory search has shown that disks can be effectively used as secondary storage when performing large breadthfirst searches. We introduce the Write-Minimizing Breadth-First Search (WMBFS) algorithm which is designed to minimize the number of writes performed in an external-memory BFS. WMBFS is also designed to store the results of the BFS for later use. We present th...