astronomy

Jan Karel Lenstra

Jan Karel Lenstra 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 Karel Lenstra rather than just read about it. In short: Jan Karel Lenstra (born 19 December 1947, in Zaandam) is a Dutch mathematician and operations researcher, known for his work on scheduling problems, the travelling salesman problem, complexity, approximation, and local search. Lenstra received his Ph.D. from the University of Amsterdam in 1976, advised by Gijsbert de Leve.

Key takeaways

Jan Karel Lenstra 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 Karel Lenstra to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jan Karel Lenstra from memory before moving on to harder problems.

Reference excerpt

Jan Karel Lenstra (born 19 December 1947, in Zaandam) is a Dutch mathematician and operations researcher, known for his work on scheduling problems, the travelling salesman problem, complexity, approximation, and local search. Lenstra received his Ph.D. from the University of Amsterdam in 1976, advised by Gijsbert de Leve. He then became a researcher at the Centrum Wiskunde & Informatica (CWI), where he remained until 1989. After taking positions at the Eindhoven University of Technology (where he became Dean of the Faculty of Mathematics and Computer Science) and the Georgia Institute of Technology, he returned to CWI as its director in 2003. He stepped down in 2011, and at that time became a CWI Fellow. He was editor-in-chief of Mathematics of Operations Research from 1993 to 1998, and of Operations Research Letters from 2002 to 2021. Lenstra became an INFORMS Fellow in 2004. In 1997, he was awarded the EURO Gold Medal, the highest distinction within Operations Research in Europe. In 2011, he was made a Knight of the Order of the Netherlands Lion, and the CWI organized a symposium in his honor. Lenstra was chair of the Mathematical Optimization Society, of the Royal Dutch Mathematical Society, and of advisory committees of the Royal Netherlands Academy of Arts and Sciences on mathematics in primary education and on digital literacy in secondary education. He chaired the committees for the Spinoza Prize and the Stevin Prize of the Dutch Science Council. Lenstra is the brother of Arjen Lenstra, Andries Lenstra, and Hendrik Lenstra, all of whom are also mathematicians. His daughter Catrien (1976) is CEO of the City of Amsterdam. He is married to Karen Aardal, who is professor of optimization at Delft University of Technology. They have two children, Lisa (1999) and Jacob (2003).

Publications Jan Karel Lenstra // DBLP, Universität Trier Peter Brucker, Jan Karel Lenstra, Alexander H.G. Rinnooy Kan. Complexity of machine scheduling problems. Annals of Discrete Mathematics 1 (1977), 343–362. Ronald L. Graham, Eugene L. Lawler, Jan Karel Lenstra, Alexander H.G. Rinnooy Kan. Optimization and approximation in deterministic sequencing and scheduling; a survey. Annals of Discrete Mathematics 5 (1979), 287–326. J. Blazewicz, Jan Karel Lenstra, Alexander H.G. Rinnooy Kan. Scheduling subject to resource constraints; classification and complexity. Discrete Applied Mathematics 5 (1983), 11–24. Eugene L. Lawler, Jan Karel Lenstra, Alexander H.G. Rinnooy Kan, David B. Shmoys (eds.). The traveling salesman problem; a guided tour of combinatorial optimization, Wiley, Chichester (1985). Jan Karel Lenstra, David B. Shmoys, Éva Tardos. Approximation algorithms for scheduling unrelated parallel machines. Mathematical Programming 46 (1990), 259–271. Peter J. M. van Laarhoven, Emile H. L. Aarts, Jan Karel Lenstra. - Job Shop Scheduling by Simulated Annealing (info) // Operations Research, 40 (1992), pp. 113-125. Eugene L. Lawler, Jan Karel Lenstra, Alexander H.G. Rinnooy Kan, David B. Shmoys. Sequencing and scheduling; algorithms and complexity. S.C. Graves, A.H.G. Rinnooy Kan, P. Zipkin (eds.). Handbooks in operations research and management science; volume 4; logistics of production and inventory, North-Holland, Amsterdam (1993), 445–522. Emile H. L. Aarts, Peter J. M. van Laarhoven, Jan Karel Lenstra, Nico L. J. Ulder: A Computational Study of Local Search Algorithms for Job Shop Scheduling. // INFORMS Journal on Computing 6(2): 118-125 (1994) (dblp) Emile H.L. Aarts, Jan Karel Lenstra. Local search in combinatorial optimization, Wiley, Chichester (1997) Jan Karel Lenstra, David B. Shmoys. elementsofscheduling.nl [1]. (This website presents fragments of an unfinished book on machine scheduling.)

References

Sources Album Academicum (website University of Amsterdam)

Illustrations

Worked examples

Example 1 — a first encounter with Jan Karel Lenstra

Start with the simplest possible case. Write down what Jan Karel Lenstra 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 Karel Lenstra 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 Karel Lenstra 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 Karel Lenstra

In research: Jan Karel Lenstra 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 Karel Lenstra 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 Karel Lenstra is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1947 births, Academic staff of the Eindhoven University of Technology, Dutch mathematicians, so understanding it makes those chapters shorter.
In everyday life: Look for Jan Karel Lenstra 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Jan Karel Lenstra” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Jan Karel Lenstra in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jan Karel Lenstra 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 Jan Karel Lenstra out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jan Karel Lenstra in simple terms?

Why does Jan Karel Lenstra 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 Karel Lenstra?

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 Karel Lenstra.