2 citations · 5 across the 10 of their papers we have counts for
11 papers
Non-Minimal -Perfect Hashing: Tight Lower Bounds and an Application to Fast Static Hash Tables
Ragnar Groot Koerkamp, Stefan Hermann, Peter Sanders +1
A minimal perfect hash function (minimal PHF) is a data structure mapping a static set of keys to bins without collisions. Two natural generalizations are minimal -PHFs…
Patching leaky tunnels in BWTs
Paola Bonizzoni, Davide Cozzi, Travis Gagie +2
We extend Baier's foundationial work on tunnelling Burrows-Wheeler Transforms (BWTs) by showing how something that would be a good tunnel except for a strings that diverge from the…
Revisiting chaining for anchored edit distance
Nicola Rizzo, Ragnar Groot Koerkamp
Colinear chaining is a classical heuristic for sequence alignment: it enables scalable genome comparison and is a main component of many state-of-the-art read mappers based on seed…
The Anti-Lexicographic SUS-Anchor: An Empirically Optimal Selection Scheme
Ragnar Groot Koerkamp
In recent years, there has been a renewed interest in the search for low density minimizer schemes. These schemes take a window of consecutive -mers, and sample one of them:…
SimdQuickHeap: The QuickHeap Reconsidered
Johannes Breitling, Ragnar Groot Koerkamp, Marvin Williams
Priority queues are data structures that maintain a dynamic collection of elements and allow inserting new elements and removing the smallest element. The most widely known and use…
QuadRank: Engineering a High Throughput Rank
R. Groot Koerkamp
Given a text, a query counts the number of occurrences of character among the first characters of the text. Space-efficient methods to answer these ra…
Compressing Suffix Trees by Path Decompositions
Ruben Becker, Davide Cenzato, Travis Gagie +4
The suffix tree is arguably the most fundamental data structure on strings: introduced by Weiner (SWAT 1973) and McCreight (JACM 1976), it allows solving a myriad of computational…
PtrHash: Minimal Perfect Hashing at RAM Throughput
Ragnar Groot Koerkamp
Given a set of keys, a minimal perfect hash function (MPHF) is a collision-free bijective map from to . This work presents a (min…
U-index: A Universal Indexing Framework for Matching Long Patterns
Lorraine A. K. Ayad, Gabriele Fici, Ragnar Groot Koerkamp +4
Text indexing is a fundamental and well-studied problem. Classic solutions either replace the original text with a compressed representation, e.g., the FM-index and its variants, o…
On rainbow-free colourings of uniform hypergraphs
Ragnar Groot Koerkamp, Stanislav Živný
We study rainbow-free colourings of -uniform hypergraphs; that is, colourings that use colours but with the property that no hyperedge attains all colours. We show that $p^*…
Stable gonality is computable
Ragnar Groot Koerkamp, Marieke van der Wegen
Stable gonality is a multigraph parameter that measures the complexity of a graph. It is defined using maps to trees. Those maps, in some sense, divide the edges equally over the e…