Today is ANZAC day in Australia and New Zealand.

Lest we forget.


SDT book review done

I’ve been reading Bunge, Gago and San Luis’s book Synthetic Differential Topology to review for MathReviews. I’ve finally sent off the written review, to appear here within short order (requires subscription).


On the whole, the book is ok, pretty much self-contained, but could have done with a bit more copy-editing. I think of this as more a fault of the publisher, but given that it’s in a lecture notes series, they probably didn’t give it as thorough a going-over. I’m very much intrigued by the link between Penon’s intrinsic topology on objects of a topos, which plays a big rôle in SDT, and Mike Shulman’s real cohesion, as hinted at in these slides by David Jaz Meyers.

(My thanks to the AMS for the free reviewers copy of the book).

Now on Twitter, almost

I have created a Twitter account for this blog, @GeometerThe @HigherGeometer.

And by linking with the blog, Twitter now demands a phone number to unlock my account as it has detected ‘suspicious activity’. Sigh. I have contacted Twitter to get this sorted.

Something I wrote…

Last year, Inference approached me to write something about the Mochizuki–Scholze–Stix affair. I had to give it serious thought, but in the end accepted. I agree with Peter Woit’s view that venues willing to publish high-end writing about mathematics and physics are too few. When I was a high-school student I devoured my library’s back catalogue of New Scientist, reading up on particle physics, astronomy, etc, learning a lot about current physics. Sadly, it seems to be more of tabloid science these days (really, for the past 15 years or more), or perhaps I just have a more informed view of what is possible in science writing.

Anyway, here’s the essay: A crisis of identification