astronomy

Otto H. Kegel

Otto H. Kegel 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 Otto H. Kegel rather than just read about it. In short: Otto Helmut Kegel (German: [ˈɔtoː ˈhɛlmuːt ˈkeːgəl]; 20 July 1934 – 20 July 2025) was a German mathematician who worked on group theory. He was a professor at the University of Freiburg.

Key takeaways

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

Reference excerpt

Otto Helmut Kegel (German: [ˈɔtoː ˈhɛlmuːt ˈkeːgəl]; 20 July 1934 – 20 July 2025) was a German mathematician who worked on group theory. He was a professor at the University of Freiburg.

Early life and career Kegel was born on 20 July 1934 in Bethlehem, Pennsylvania. His parents were German, and the family returned to Germany in 1938. He attended high school in Frankfurt am Main. Kegel received his PhD from Goethe University Frankfurt in 1961, with a thesis titled Vertauschbarkeit von Untergruppen und Kompositionsstruktur in endlichen Gruppen (Commutability of subgroups and composition structure in finite groups) and supervised by Reinhold Baer. He completed his habilitation at the same institution in 1966. In 1962, Kegel gave a talk titled Locally finite groups with a partition at the International Congress of Mathematicians, in Stockholm, Sweden. Kegel started at Queen Mary College in the University of London as a reader in 1968, and was promoted to professor in 1970. He moved to the University of Freiburg beginning in 1975, where he worked as a professor until his retirement in 1999. He was an editor for Archiv der Mathematik from 1975 until 1990.

Death Kegel died on 20 July 2025, his 91st birthday.

Research Kegel worked in the field of group theory, a part of abstract algebra. His book on locally finite groups, written with Bertram Wehrfritz, was influential in the subfield. Prime graphs are also known as Gruenberg-Kegel graphs due to early unpublished work of Kegel with Karl W. Gruenberg on the topic.

Awards and honors In 1985, Archiv der Mathematik dedicated an issue to Kegel, in honor of his contributions to the journal as an author, editor, and on the advisory board. A conference Algebra and Group Theory was held in Kegel's honor at the University of Upper Alsace in 2015. The 2024 edition of the Ischia Group Theory conference was also dedicated to Kegel, marking his 90th birthday.

Selected publications Kegel, Otto H. (1962). "Sylow-Gruppen und Subnormalteiler endlicher Gruppen". Mathematische Zeitschrift. 78: 205–221. doi:10.1007/BF01195169. MR 0147527. Zbl 0082.24703. Kegel, Otto H.; Wehrfritz, Bertram A. F. (1973). Locally finite groups. North-Holland Publishing Co. MR 0470081. Zbl 0259.20001.

References

Illustrations

Worked examples

Example 1 — a first encounter with Otto H. Kegel

Start with the simplest possible case. Write down what Otto H. Kegel 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 Otto H. Kegel 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 Otto H. Kegel 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 Otto H. Kegel

In research: Otto H. Kegel 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 Otto H. Kegel 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: Otto H. Kegel is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1934 births, 2025 deaths, 20th-century German mathematicians, so understanding it makes those chapters shorter.
In everyday life: Look for Otto H. Kegel 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 Otto H. Kegel in 20 minutes

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

Frequently asked questions

What is Otto H. Kegel in simple terms?

Otto Helmut Kegel (German: [ˈɔtoː ˈhɛlmuːt ˈkeːgəl]; 20 July 1934 – 20 July 2025) was a German mathematician who worked on group theory. He was a professor at the University of Freiburg.

Why does Otto H. Kegel 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 Otto H. Kegel?

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 Otto H. Kegel.