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Lucy Hawking Award Winner 2013



Today's Theorem   on Monday 30 November, 2020

Yesterday's Theorem     Tomorrow's Theorem     Complete Listing


Welcome to a gallery whose exhibits are the crowning achievements of mathematics: her theorems.

The first 20 terms of the Fibonacci sequence

Each day offers a different theorem (or lemma, law, formula or identity), each one worthy of adorning the walls of a mathematical Abattoirs, Baltic, Duniya, Guggenheim, Louvre, Nail Factory, Staatliche Museen, Tate, Uffizi or Zach Feuer.

Each theorem has been presented so as to be appreciated by as wide an audience as possible. If the statement of the theorem appears obscure, pass on to the illustration and its accompanying explanation. If it still seems hard it is probably because it is hard. But no more than O'Keeffe's Blue and Green Music, say, is a 'hard' painting or Hepworth's Two Figures is a 'hard' sculpture. It is there for you to engage with on your own terms.

By 'engage' I mean: admire it, turn it over in your mind, try to follow the example, if one is given; if you are studying it on-line, follow the web link, which will provide a pictorial interpretation, a proof or even a clever animation.

Click on the 'further reading' link. It will usually take you to the page for the book. This is a convenient way to provide full bibliographical details of the book and often, a preview of its contents; it is not a recommendation that you buy the book (but, if you do, this website earns a small referral fee).

Each theorem is as self-contained as possible; when viewing a theorem on-line, the Glossary icon button, top-right, links to a Glossary page where there is a brief explanation of some parts of mathematical language; an accompanying Notes icon indicates that the theorem has been provided with some supplementary information often by expert visitors to the page. At the bottom of the page, the Back arrow icon arrow will take you to a related but usually less sophisticated theorem which may shed light on today's; the Theorem List Icon button will take you to the complete theorem list; and the Forward arrow icon arrow may point to a theorem which leads on from today's or takes you deeper into its subject. For some theorems are deeper than others; some use more technical language than others; some are just harder to understand than others.

Some days are harder than others. I hope even the most difficult days offer something of wonder.

Recent Acquisitions

The Cauchy-Frobenius Lemma (French)
The Cauchy-Frobenius Lemma (French)

coming soon...

more beautiful theorems!
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Beeley, Nasifoglu and Wardhaugh, Reading Mathematics in Early Modern Europe
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Theorem of the Day is maintained by Robin Whitty. Comments or suggestions are welcomed by me.
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