PeopleofSuperintelligence

Researcher

Rico Sennrich

Rico Sennrich is a natural language processing researcher whose 2016 work on subword units for machine translation underpins the tokenization used in virtually all of today's large language models. After a master's at the University of Zurich from 2004 to 2010 and a PhD in computational linguistics from 2010 to 2013, he worked at the University of Edinburgh from 2013, first as an SNSF mobility fellow and then as research associate and lecturer. In 2016, with Barry Haddow and Alexandra Birch, he published the Byte Pair Encoding paper and a back-translation paper, and built neural translation systems for WMT 2016 that were the tied best constrained system in seven of eight directions; the Nematus toolkit followed in 2017. He moved to Zurich in 2019 as an SNSF Professor and received the ACL 2026 Test-of-Time Award for the Byte Pair Encoding paper. Since February 2026, he is an Associate Professor at the University of Zurich, working on machine translation and multilinguality.

Born
1985
Works
369
Citations
9,045
h-index
44
Badges

Years link to their sources. Publication numbers from OpenAlex, as of 22 October 2026.

Timeline

  1. 2004–2013

    Zurich studies and a PhD

    He studies at the University of Zurich from 2004 to 2010, majoring in English Language and Literature with minors in Computational Linguistics and Educational Science, and spends 2006–2007 on an Erasmus year at Lancaster University. A PhD in computational linguistics follows from 2010 to 2013, within the project Domain-specific Statistical Machine Translation.

  2. 2013–2017

    Edinburgh fellow and research associate

    From 2013 to 2015, he holds an SNSF mobility fellowship at the University of Edinburgh, working on improving fluency with syntax-based statistical machine translation. He stays on as a research associate at Edinburgh until 2017.

  3. 2016

    Byte Pair Encoding for translation

    In 2016, he publishes 'Neural Machine Translation of Rare Words with Subword Units' with Barry Haddow and Alexandra Birch at ACL. The paper adapts Byte Pair Encoding, a compression algorithm, to split words into smaller subword units, which lets translation systems handle rare and previously unseen words.

  4. 2016

    Back-translation with monolingual data

    At ACL in 2016, he presents 'Improving Neural Machine Translation Models with Monolingual Data' with Barry Haddow and Alexandra Birch. Pairing monolingual training data with an automatic back-translation turns it into additional parallel training data and adds 2.8 to 3.7 BLEU on the WMT 15 English–German task.

  5. 2016–2017

    WMT 16 systems and Nematus

    In 2016, the neural translation systems he builds with Barry Haddow and Alexandra Birch for English paired with Czech, German, Romanian and Russian are the (tied) best constrained system in 7 of 8 directions at WMT 2016. In 2017, he is first author of Nematus, a neural machine translation toolkit used to build top-performing WMT and IWSLT submissions.

  6. 2017–2025

    Edinburgh lecturer and Zurich professor

    He is Lecturer (Assistant Professor) at the University of Edinburgh from 2017 to 2022 and a part-time researcher at the University of Zurich until 2019. In 2019, he moves to Zurich to take up an SNSF Professorship, which runs until 2025.

  7. 2026

    An ACL Test-of-Time Award

    In 2026, he receives the ACL 2026 Test-of-Time Paper Award for the 2016 Byte Pair Encoding paper with Barry Haddow and Alexandra Birch, presented at ACL 2026 in San Diego. The subword method it introduced underpins the tokenization used in virtually all of today's large language models.

  8. Since February 2026

    Associate Professor at Zurich

    In February 2026, he becomes Associate Professor at the University of Zurich's Department of Computational Linguistics. His work covers machine translation and multilinguality, low-resource and efficient methods, interpretability and model analysis, and multimodal language processing.

Career

  1. Since 2019University of ZurichPart-time researcher, SNSF Professor
  2. 2013–2022University of EdinburghSNSF mobility fellow, Research associate

Education

  1. 2013University of ZurichPhD
  2. 2010University of ZurichMaster's
  3. 2007Lancaster UniversityErasmus student

From the biography and OpenAlex affiliations (the years of papers that list the organization), so some years are approximate.

Most-cited works

  1. Analyzing Multi-Head Self-Attention: Specialized Heads Do the Heavy Lifting, the Rest Can Be Pruned2019 · Annual Meeting of the Association for Computational Linguistics (ACL) · 1,139 citationsWith Ivan Titov
  2. Neural Machine Translation of Rare Words with Subword Units2016 · Annual Meeting of the Association for Computational Linguistics (ACL) · 936 citations
  3. Nematus: a Toolkit for Neural Machine Translation2017 · 293 citationsWith Kyunghyun Cho
  4. Context-Aware Neural Machine Translation Learns Anaphora Resolution2018 · Annual Meeting of the Association for Computational Linguistics (ACL) · 285 citationsWith Ivan Titov
  5. Has Machine Translation Achieved Human Parity? A Case for Document-level Evaluation2018 · Conference on Empirical Methods in Natural Language Processing (EMNLP) · 284 citations

From OpenAlex, as of 21 October 2026.

  1. The Massachusetts Institute of Technology trained or employed 44 of the 187 AI major-prize winners, more than any other universityIncludes University of Zurich. The Massachusetts Institute of Technology trained or employed 44 of the 187 AI major-prize winners, more than any other university. We compare doctorate and 5+ year employment links, career timing and current workplaces for 187 major-prize and 1,111 best-paper winners.
  2. More people shaping AI studied at Massachusetts Institute of Technology than at any other institutionIncludes University of Zurich. We estimate where the people shaping AI studied and where their careers led. Massachusetts Institute of Technology leads with 467 former students, including 291 recorded doctorates.
  3. The company share of AI researchers’ top papers was 31% in 2020–2024 and 8% in 1970–1974Includes University of Zurich. We estimate where the people shaping AI worked when their most-cited papers appeared: the company share was 31% in 2020–2024 and 8% in 1970–1974, and Google led all organizations in 2020–2024.
  4. Google has the highest combined h-index among AI organizationsIncludes University of Zurich. We estimate that Google holds the highest combined h-index at 8,016, while universities account for 73% of the deduplicated total across AI organizations.

Colleagues

People named in this biography, and people with dated positions at the same organization in the same years.

Sources and credits

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  1. Rico Sennrich, CV | Department of Computational Linguistics | UZH cl.uzh.ch. Checked 20 October 2026.
  2. ACL Honours UZH Professor for research that helped shape today's AI systems | UZH.ai | UZH ai.uzh.ch. Checked 20 October 2026.
  3. Informatics research recognised with two ACL Test-of-Time Awards | School of Informatics informatics.ed.ac.uk. Checked 20 October 2026.
  4. [1511.06709] Improving Neural Machine Translation Models with Monolingual Data arxiv.org. Checked 20 October 2026.
  5. Improving Neural Machine Translation Models with Monolingual Data - ACL Anthology aclanthology.org. Checked 20 October 2026.
  6. [1606.02891] Edinburgh Neural Machine Translation Systems for WMT 16 arxiv.org. Checked 20 October 2026.
  7. Nematus: a Toolkit for Neural Machine Translation - ACL Anthology aclanthology.org. Checked 20 October 2026.
  8. Congratulations: ACL Test of Time Award for Rico Sennrich | Digital Society Initiative | UZH dsi.uzh.ch. Checked 20 October 2026.
  9. Rico Sennrich | Department of Computational Linguistics | UZH cl.uzh.ch. Checked 20 October 2026.