Stephen Robertson is a British computer scientist. He is known for his work on probabilistic information retrieval together with

Karen Spärck Jones Karen Sparck Jones is a computer science researcher and innovator who pioneered the search engine algorithm known as inverse document frequency (IDF). While many early information scientists and computer engineers were focused on developing progr ...

and the

Okapi BM25 The okapi (; ''Okapia johnstoni''), also known as the forest giraffe, Congolese giraffe, or zebra giraffe, is an artiodactyl mammal that is endemic to the northeast Democratic Republic of the Congo in central Africa. It is the monotypic taxon ...

weighting model.

is very successful in experimental search evaluations and found its way in many information retrieval systems and products, including open source search systems like

Lucene Apache Lucene is a free and open-source search engine software library, originally written in Java by Doug Cutting. It is supported by the Apache Software Foundation and is released under the Apache Software License. Lucene is widely used as ...

Lemur Lemurs ( ) (from Latin ''lemures'' – ghosts or spirits) are wet-nosed primates of the superfamily Lemuroidea (), divided into 8 families and consisting of 15 genera and around 100 existing species. They are endemic to the island of Madagas ...

Xapian Xapian is a free and open-source probabilistic information retrieval library, released under the GNU General Public License (GPL). It is a full-text search engine library for programmers. It is written in C++, with bindings to allow use from ...

, and

Terrier Terrier (from Latin ''terra'', 'earth') is a type of dog originally bred to hunt vermin. A terrier is a dog of any one of many breeds or landraces of the terrier type, which are typically small, wiry, game, and fearless. Terrier breeds vary ...

. BM25 is used as one of the most important signals in large web search engines, certainly in

Microsoft Bing Microsoft Bing (commonly known as Bing) is a web search engine owned and operated by Microsoft. The service has its origins in Microsoft's previous search engines: MSN Search, Windows Live Search and later Live Search. Bing provides a variety ...

, and probably in other web search engines too. BM25 is also used in various other Microsoft products such as Microsoft

SharePoint SharePoint is a web-based collaborative platform that integrates natively with Microsoft Office. Launched in 2001, SharePoint is primarily sold as a document management and storage system, but the product is highly configurable and its usage v ...

and SQL Server. After completing his undergraduate degree in mathematics at

Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209 and granted a royal charter by Henry III of England, Henry III in 1231, Cambridge is the world' ...

, he took an MS at City University, and then worked for

ASLIB ASLIB: The Association for Information Management (often stylized ''Aslib'') was a British association of special libraries and information centres. It was founded in England in 1924 as the Association of Special Libraries and Information Bureaux. ...

. He earned his PhD at

University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = ...

in 1976 under the renowned statistician and scholar B. C. Brookes. He then returned to City University working there from 1978 until 1998 in the Department of

Information Science Information science (also known as information studies) is an academic field which is primarily concerned with analysis, collection, classification, manipulation, storage, retrieval, movement, dissemination, and protection of informatio ...

, continuing as a part-time professor and subsequently as professor emeritus. He is also a fellow of

Girton College Girton College is one of the Colleges of the University of Cambridge, 31 constituent colleges of the University of Cambridge. The college was established in 1869 by Emily Davies and Barbara Bodichon as the first women's college in Cambridge. In 1 ...

, Cambridge University. Now retired, Robertson is Professor Emeritus at City University, and a Visiting Professor in the Department of Computer Science at UCL.

References

Publications

* * {{DEFAULTSORT:Robertson, Stephen British computer scientists Alumni of University College London Fellows of Girton College, Cambridge Living people Alumni of City, University of London Academics of City, University of London Information retrieval researchers 1946 births