ArticleslgStudy

science

Strictification

Strictification is a science 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 Strictification rather than just read about it. In short: In mathematics, specifically in category theory, a strictification refers to statements of the form “every weak structure of some sort is equivalent to a stricter one.” Such a result was first proven for monoidal categories by Mac Lane, and it is often possible to derive strictifications from coherence results and vice versa. Monoidal category Every monoidal category is monoidally equivalent to a strict monoidal cat…

Key takeaways

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

Reference excerpt

In mathematics, specifically in category theory, a strictification refers to statements of the form “every weak structure of some sort is equivalent to a stricter one.” Such a result was first proven for monoidal categories by Mac Lane, and it is often possible to derive strictifications from coherence results and vice versa.

Monoidal category Every monoidal category is monoidally equivalent to a strict monoidal category. This is (essentially) the Mac Lane coherence theorem.

See also Coherence condition

Notes

References Schauenburg, Peter (2001). "Turning monoidal categories into strict ones". The New York Journal of Mathematics [Electronic Only]. 7: 257–265. ISSN 1076-9803. Joyal, A.; Street, R. (1993). "Braided Tensor Categories". Advances in Mathematics. 102 (1): 20–78. doi:10.1006/aima.1993.1055. Lack, Stephen (2002). "Codescent objects and coherence". Journal of Pure and Applied Algebra. 175 (1–3): 223–241. doi:10.1016/S0022-4049(02)00136-6. Mac Lane, Saunders (1978). "Symmetry and Braidings in Monoidal Categories". Categories for the Working Mathematician. Graduate Texts in Mathematics. Vol. 5. pp. 251–266. doi:10.1007/978-1-4757-4721-8_12. ISBN 978-1-4419-3123-8. §3. Strict Monoidal Categories Shulman, Michael A. (2012). "Not every pseudoalgebra is equivalent to a strict one". Advances in Mathematics. 229 (3): 2024–2041. arXiv:1005.1520. doi:10.1016/j.aim.2011.01.010.

External links Etingof, Pavel; Gelaki, Shlomo; Nikshych, Dmitri; Ostrik, Victor. "18.769, Spring 2009, Graduate Topics in Lie Theory: Tensor Categories §.Lecture 2". MIT Open Course Ware.

Worked examples

Example 1 — a first encounter with Strictification

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

In research
Strictification appears in science 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 Strictification 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
Strictification is common in secondary-school and first-year university syllabi. It links to neighbouring topics Category theory, so understanding it makes those chapters shorter.
In everyday life
Look for Strictification 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.

Affiliate

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

How to study Strictification in 20 minutes

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

Frequently asked questions

What is Strictification in simple terms?

In mathematics, specifically in category theory, a strictification refers to statements of the form “every weak structure of some sort is equivalent to a stricter one.” Such a result was first proven for monoidal categories by Mac Lane, and it is often possible to derive strictifications from coher…

Why does Strictification matter?

Because it connects several science 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 Strictification?

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 Strictification.

Tags

  • Category theory

Keep exploring