chemistry

Haruo Hosoya

Haruo Hosoya is a chemistry 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 Haruo Hosoya rather than just read about it. In short: Haruo Hosoya (Japanese: 細矢治夫, Hepburn: Hosoya Haruo; born 1936) is a Japanese chemist and emeritus professor of Ochanomizu University, Tokyo, Japan. He is the namesake of the Hosoya index used in discrete mathematics and computational chemistry.

Key takeaways

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

Reference excerpt

Haruo Hosoya (Japanese: 細矢治夫, Hepburn: Hosoya Haruo; born 1936) is a Japanese chemist and emeritus professor of Ochanomizu University, Tokyo, Japan. He is the namesake of the Hosoya index used in discrete mathematics and computational chemistry.

Early life Hosoya was born in Kamakura, Japan to a family of an office worker. During 1955-1959 he studied at the University of Tokyo. In 1964 he wrote his Ph.D. thesis, "Study on the Structure of Reactive Intermediates and Reaction Mechanism".

Career After postdoc work abroad (Ann Arbor, Michigan, with prof. John Platt), in 1969 he became associate professor at the Ochanomizu University, where he worked for 33 years until his retirement in 2002. After retirement he has kept working in computational chemistry. In 1971, Hosoya defined the topological index (a graph invariant) now known as the Hosoya index as the total number of matchings of a graph plus 1. The Hosoya index is often used in computer (mathematical) chemistry investigations for organic compounds. In 2002-2003 the Internet Electronic Journal of Molecular Design dedicated a series of issues to commemorate the 65th birthday of professor Hosoya. Hosoya's article "The Topological Index Z Before and After 1971" describes the history of the notion and the associated inside stories and details other Hosoya's achievements. Hosoya also introduced the triangle of numbers known as Hosoya's triangle (originally "Fibonacci triangle", but that name can be ambiguous).

Notes

Worked examples

Example 1 — a first encounter with Haruo Hosoya

Start with the simplest possible case. Write down what Haruo Hosoya claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 Haruo Hosoya 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 Haruo Hosoya 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 Haruo Hosoya

In research: Haruo Hosoya appears in chemistry 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 Haruo Hosoya 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: Haruo Hosoya is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1936 births, Academic staff of Ochanomizu University, Chemist stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Haruo Hosoya 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 Haruo Hosoya in 20 minutes

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

Frequently asked questions

What is Haruo Hosoya in simple terms?

Why does Haruo Hosoya matter?

Because it connects several chemistry 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 Haruo Hosoya?

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 Haruo Hosoya.