Back from Boston

I spent the end of last week in Cambridge, where I gave a talk at MIT about the homology of Hurwitz spaces.

• Good addition to Harvard Square: there’s now a used-book table on Mass Ave, like the ones I used to patronize on Broadway in Morningside Heights. I flipped through “Strike From Space,” a 1965 book by Phyllis Schlafly and Lester Ward, with the thesis that dopey Democrats were getting head-faked by the Soviets into escalating our commitment to Vietnam, which conflict was in fact not the firewall against an all-red Asia but a mere Soviet plot to distract us from an imminent nuclear first strike from orbit. Bad addition to Harvard Square: a Qdoba! I thought fast food was forbidden from Harvard Square by zoning laws, but apparently you can apply for an exemption — here’s Chipotle’s application to open a restaurant at One Brattle Square.
• I had the pleasure of meeting Andy Putman and learning about a beautiful recent theorem of his; the moduli space of genus-g curves with full level N structure has the same second homology as M_g itself, for g at least 5. As a corollary, all these spaces have Picard number 1. I also learned a lot from Denis Auroux about mapping class group factorizations and symplectic Lefschetz fibrations — but more on this when I write a post or two on Hurwitz spaces.  Update: (25 Sep 08) Putman’s paper is now on the arXiv.