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astronomy

Jan Saxl

Jan Saxl is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jan Saxl rather than just read about it. In short: Jan Saxl (5 June 1948 – 2 May 2020) was a Czech-British mathematician, and a professor at the University of Cambridge. He was known for his work in finite group theory, particularly on consequences of the classification of finite simple groups.

Jan Saxl — main illustration
Jan Saxl — illustration

Key takeaways

  • Jan Saxl belongs to astronomy; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Jan Saxl to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Jan Saxl from memory before moving on to harder problems.

Reference excerpt

Jan Saxl (5 June 1948 – 2 May 2020) was a Czech-British mathematician, and a professor at the University of Cambridge. He was known for his work in finite group theory, particularly on consequences of the classification of finite simple groups.

Education and career Saxl was born in Brno, in what was at the time Czechoslovakia. He came to the United Kingdom in 1968, during the Prague Spring. After undergraduate studies at the University of Bristol, he completed his DPhil in 1973 at the University of Oxford under the direction of Peter M. Neumann, with the title of Multiply Transitive Permutation Groups. Saxl held postdoctoral positions at Oxford and the University of Illinois at Chicago, and a lecturer position at the University of Glasgow. He moved to the University of Cambridge in 1976, and spent the rest of his career there. He was elected as a fellow of Gonville and Caius College in 1986, and he retired in 2015. Saxl published around 100 papers, and according to MathSciNet, these have been cited over 1900 times. He is noted for his work in finite group theory, particularly on permutation groups, and often coauthored with Robert Guralnick, Martin Liebeck, and Cheryl Praeger. Some notable and highly-cited examples of this work are as follows. Liebeck, Saxl and Praeger gave a relatively simple and self-contained proof of the O'Nan–Scott theorem. It had long been known that every maximal subgroup of a symmetric group or alternating group was intransitive, imprimitive, or primitive, and the same authors in 1988 gave a partial description of which primitive subgroups could occur.

Personal life Saxl was married to Cambridge mathematician Ruth M. Williams and they had one daughter, Miriam.

Death Saxl died on 2 May 2020, after a long period of poor health.

Awards and honors A three-day conference in the joint honor of Saxl and Martin Liebeck was held at the University of Cambridge in July 2015.

Publications

Books

Liebeck, Martin; Praeger, Cheryl; Saxl, Jan (2010). "Regular subgroups of primitive permutation groups". Memoirs of the American Mathematical Society. 203 (952). American Mathematical Society (AMS). doi:10.1090/s0065-9266-09-00569-9. ISBN 978-0-8218-4654-4. ISSN 0065-9266. MR 2588738. OCLC 457767029.{{cite journal}}: CS1 maint: periodical has ISBN (link) Guralnick, Robert M.; Müller, Peter; Saxl, Jan (2003). "The rational function analogue of a question of Schur and exceptionality of permutation representations". Memoirs of the American Mathematical Society. 162 (773). American Mathematical Society (AMS). arXiv:math/0201069. doi:10.1090/memo/0773. ISBN 9780821832882. ISSN 0065-9266. MR 1955160. S2CID 7113361.{{cite journal}}: CS1 maint: periodical has ISBN (link) Ivanov, Alexander A.; Liebeck, Martin W.; Saxl, Jan, eds. (2003). Groups combinatorics & geometry : Durham 2001. New Jersey London: World Scientific. ISBN 981-238-312-3. OCLC 228115554. Liebeck, Martin W.; Saxl, Jan, eds. (1992). Groups, combinatorics & geometry : Durham, 1990. Cambridge England New York: Cambridge University Press. ISBN 978-0-521-40685-7. OCLC 839544039. Liebeck, Martin W.; Praeger, Cheryl E.; Saxl, Jan (1990). "The maximal factorizations of the finite simple groups and their automorphism groups". Memoirs of the American Mathematical Society. 86 (432). American Mathematical Society (AMS). doi:10.1090/memo/0432. ISBN 9780821861554. ISSN 0065-9266. MR 1016353.{{cite journal}}: CS1 maint: periodical has ISBN (link) Selected articles

Liebeck, Martin W.; Praeger, Cheryl E.; Saxl, Jan (1988). "On the O'Nan-Scott theorem for finite primitive permutation groups". Journal of the Australian Mathematical Society, Series A. 44 (3). Cambridge University Press (CUP): 389–396. doi:10.1017/s144678870003216x. ISSN 0263-6115.

References

Illustrations

Jan Saxl illustration

Worked examples

Example 1 — a first encounter with Jan Saxl

Start with the simplest possible case. Write down what Jan Saxl claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jan Saxl before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jan Saxl ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jan Saxl

In research
Jan Saxl appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Jan Saxl in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Jan Saxl is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1948 births, 2020 deaths, Alumni of the University of Bristol, so understanding it makes those chapters shorter.
In everyday life
Look for Jan Saxl outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Jan Saxl in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Jan Saxl means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Jan Saxl out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jan Saxl in simple terms?

Jan Saxl (5 June 1948 – 2 May 2020) was a Czech-British mathematician, and a professor at the University of Cambridge. He was known for his work in finite group theory, particularly on consequences of the classification of finite simple groups.

Why does Jan Saxl matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jan Saxl?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jan Saxl.

Tags

  • 1948 births
  • 2020 deaths
  • Alumni of the University of Bristol
  • Alumni of the University of Oxford
  • Cambridge mathematicians
  • Czech emigrants to the United Kingdom
  • Czech mathematicians
  • Fellows of Gonville and Caius College, Cambridge
  • Group theorists
  • Scientists from Brno
  • University of Illinois Chicago people

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