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Jun-Ichi Igusa

Jun-Ichi Igusa is a mathematics 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 Jun-Ichi Igusa rather than just read about it. In short: Jun-ichi Igusa (井草 凖一, Igusa Jun’ichi; 30 January 1924 – 24 November 2013) was a Japanese mathematician who for over three decades was on the faculty at Johns Hopkins University. He is known for his contributions to algebraic geometry and number theory.

Key takeaways

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

Reference excerpt

Jun-ichi Igusa (井草 凖一, Igusa Jun’ichi; 30 January 1924 – 24 November 2013) was a Japanese mathematician who for over three decades was on the faculty at Johns Hopkins University. He is known for his contributions to algebraic geometry and number theory. The Igusa zeta-function, the Igusa quartic, Igusa subgroups, Igusa curves, and Igusa varieties are named after him. He was an invited speaker for the 1962 International Congress of Mathematicians in Stockholm. He was awarded Japan's Order of the Sacred Treasure. In 2012 he became a fellow of the American Mathematical Society.

Life and career Igusa was born in Kiyosato village, Gunma Prefecture, Japan, on 30 January 1924. He graduated from the University of Tokyo in 1945 and received his Ph.D. from Kyoto University in 1953, after which he became professor of mathematics at the University of Tsukuba. After a brief period spent at Harvard University, he took up a permanent position at Johns Hopkins University, in Baltimore. Igusa taught at Johns Hopkins from 1955 to 1993. He joined the staff of the American Journal of Mathematics as an associate editor in 1964, and served as chief editor between 1978 and 1993. Igusa died, aged 89, of a stroke at Holly Hill Nursing Home in Towson, Maryland, on 24 November 2013. He had three sons, Kiyoshi, Takeru and Mitsuru. Takeru Igusa is a professor of civil engineering at Johns Hopkins University. Kiyoshi Igusa is a professor of mathematics at Brandeis University.

Publications Igusa, Jun-ichi (1972), Theta functions, Die Grundlehren der mathematischen Wissenschaften, vol. 194, Berlin, New York: Springer-Verlag, ISBN 978-3-540-05699-7, MR 0325625 Igusa, Jun-ichi (1978), Forms of higher degree (PDF), Tata Institute of Fundamental Research Lectures on Mathematics and Physics, vol. 59, Bombay: Tata Institute of Fundamental Research, ISBN 978-0-387-08944-7, MR 0546292 Igusa, Jun-ichi (2000), An introduction to the theory of local zeta functions, AMS/IP Studies in Advanced Mathematics, vol. 14, Providence, R.I.: American Mathematical Society, ISBN 978-0-8218-2015-5, MR 1743467

References

Worked examples

Example 1 — a first encounter with Jun-Ichi Igusa

Start with the simplest possible case. Write down what Jun-Ichi Igusa claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 Jun-Ichi Igusa 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 Jun-Ichi Igusa 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 Jun-Ichi Igusa

In research
Jun-Ichi Igusa appears in mathematics 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 Jun-Ichi Igusa 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
Jun-Ichi Igusa is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1924 births, 2013 deaths, 20th-century Japanese mathematicians, so understanding it makes those chapters shorter.
In everyday life
Look for Jun-Ichi Igusa 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 Jun-Ichi Igusa in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Jun-Ichi Igusa 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 Jun-Ichi Igusa out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jun-Ichi Igusa in simple terms?

Jun-ichi Igusa (井草 凖一, Igusa Jun’ichi; 30 January 1924 – 24 November 2013) was a Japanese mathematician who for over three decades was on the faculty at Johns Hopkins University. He is known for his contributions to algebraic geometry and number theory.

Why does Jun-Ichi Igusa matter?

Because it connects several mathematics 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 Jun-Ichi Igusa?

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 Jun-Ichi Igusa.

Tags

  • 1924 births
  • 2013 deaths
  • 20th-century Japanese mathematicians
  • 21st-century Japanese mathematicians
  • Academic journal editors
  • Academic staff of the University of Tsukuba
  • Fellows of the American Mathematical Society
  • Harvard University Department of Mathematics faculty
  • Japanese expatriates in the United States
  • Johns Hopkins University faculty
  • Kyoto University alumni
  • Recipients of the Order of the Sacred Treasure, 3rd class

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