Wavelet trees, part 1

We discuss how wavelet trees partition the alphabet in order to enable rank/select/access (RSA) queries over strings. We define the RSA queries with respect to strings and illustrate the algorithms for each of those queries. ── Course & channel links ── Course playlist: Burrows-Wheeler Indexing    • Burrows-Wheeler Indexing   ── About the author ── Ben Langmead is a Professor of Computer Science at Johns Hopkins University, where his research spans bioinformatics, computational biology, and data-intensive science. He is the author of Bowtie and Bowtie 2; his group has also developed software like Kraken 2 and resources like recount3 and Index Zone, as well as methods for pangenome indexing and querying, based on e.g. the r-index and move structure. His group's methods have been cited over 130,000 times, and he is the winner of awards including an NSF CAREER award, a Sloan Research Fellowship, the Benjamin Franklin award for contributions to open access, and multiple awards for teaching and mentorship. Ben is the founder and principal of InOrder Labs LLC (https://inorderlabs.com), an expert consulting firm in bioinformatics and computational biology. Channel:    / @benlangmead   Teaching materials: https://langmead-lab.org/teaching.html