A fan writes

Why CMAJ writes editorials.

Euclid Writes an Algorithm: A Fairytale

How Euclid might have written and checked the correctness of his famous algorithm had he been a little further ahead of his time. Euclid of Alexandria was thinking. A traveler had that morning told him of a marvelous thing he had learned many years earlier from Eudoxus of Cnidus: a marvelous way to find the greatest common divisor of two numbers. But Eudoxus had not revealed the proof, and Eucl...

Truly Non-blocking Writes

Writing data within user or operating system memory often encounters the classic read-before-write problem whereby the page written to must first be read from the backing store, effectively blocking the writing process before modifications are made. Unfortunately, the large gap between memory and storage access performance adversely affects workloads that require substantial readbefore-write op...

Non-blocking Writes to Files

Writing data to a page not present in the file-system page cache causes the operating system to synchronously fetch the page into memory first. Synchronous page fetch defines both policy (when) and mechanism (how), and always blocks the writing process. Non-blocking writes eliminate such blocking by buffering the written data elsewhere in memory and unblocking the writing process immediately. S...

A Zq-Fan theorem

In 1952, Ky Fan proved a combinatorial theorem generalizing the Borsuk-Ulam theorem stating that there is no Z2-equivariant map from the d-dimensional sphere S to the (d − 1)-dimensional sphere Sd−1. The aim of the present paper is to provide the same kind of combinatorial theorem for Dold's theorem, which is a generalization of the Borsuk-Ulam theorem when Z2 is replaced by Zq, and the spheres...