# Erica Klarreich

My work has appeared in Quanta, Nature, New Scientist, Science News, Wired.com and many other publications, and has been reprinted in the 2010, 2011, and 2016 volumes of "The Best Writing on Mathematics."

klarreic@nasw.org
@EricaKlarreich

# All Is Not Fair in Cake-Cutting and Math

October 7, 2016 — A pair of computer scientists recently settled one of the key questions in the theory of fair division: How can you allocate cake slices among a group of people in such a way that no one envies anyone else? Yet envy-freeness is just one of several competing notions of fairness. It’s all well and good to divide a cake in a way that won’t produce envy, but you might instead want to find an “efficient” allocation, one that can’t be improved for anyone without harming someone else.

# How to Cut Cake Fairly and Finally Eat It Too

October 6, 2016 — Two young computer scientists have figured out how to fairly divide cake among any number of people, setting to rest a problem mathematicians have struggled with for decades. Their work has startled many researchers who believed that such a fair-division protocol was probably impossible. People have known at least since biblical times that there’s a way to divide such an object between two people so that neither person envies the other: one person cuts the cake into two slices that she values equally, and the other person gets to choose her favorite slice.

# The Oracle of Arithmetic

June 28, 2016 — In 2010, a startling rumor filtered through the number theory community and reached Jared Weinstein. Apparently, some graduate student at the University of Bonn in Germany had written a paper that redid “Harris-Taylor” — a 288-page book dedicated to a single impenetrable proof in number theory — in only 37 pages.

# Simple Set Game Proof Stuns Mathematicians

May 31, 2016 — In a series of papers posted online in recent weeks, mathematicians have solved a problem about the pattern-matching card game Set that predates the game itself. The solution, whose simplicity has stunned mathematicians, is already leading to advances in other combinatorics problems. Invented in 1974, Set has a simple goal: to find special triples called “sets” within a deck of 81 cards.

# Sphere Packing Solved in Higher Dimensions

March 30, 2016 — In a pair of papers posted online this month, a Ukrainian mathematician has solved two high-dimensional versions of the centuries-old “sphere packing” problem. In dimensions eight and 24 (the latter dimension in collaboration with other researchers), she has proved that two highly symmetrical arrangements pack spheres together in the densest possible way.

# Mathematicians Discover Prime Conspiracy

March 13, 2016 — Two mathematicians have uncovered a simple, previously unnoticed property of prime numbers — those numbers that are divisible only by 1 and themselves. Prime numbers, it seems, have decided preferences about the final digits of the primes that immediately follow them. Among the first billion prime numbers, for instance, a prime ending in 9 is almost 65 percent more likely to be followed by a prime ending in 1 than another prime ending in 9.

# ‘Outsiders’ Crack 50-Year-Old Math Problem

November 24, 2015 — In 2008, Daniel Spielman told his Yale University colleague Gil Kalai about a computer science problem he was working on, concerning how to “sparsify” a network so that it has fewer connections between nodes but still preserves the essential features of the original network. Network sparsification has applications in data compression and efficient computation, but Spielman’s particular problem suggested something different to Kalai.

# A Magical Answer to an 80-Year-Old Puzzle

October 1, 2015 — The mathematician Terence Tao, of the University of California, Los Angeles, has presented a solution to an 80-year-old number theory problem posed by the legendary Hungarian mathematician Paul Erdős. Erdős was famous for the thousands of puzzles he came up with, many of which have led to surprisingly deep mathematical discoveries.

# The Connoisseur of Number Sequences

August 6, 2015 — Neil Sloane is considered by some to be one of the most influential mathematicians of our time. That’s not because of any particular theorem the 75-year-old Welsh native has proved, though over the course of a more than 40-year research career at Bell Labs (later AT&T Labs) he won numerous awards for papers in the fields of combinatorics, coding theory, optics and statistics.

# A Design Dilemma Solved, Minus Designs

June 9, 2015 — In 1850, the Reverend Thomas Kirkman, rector of the parish of Croft-with-Southworth in Lancashire, England, posed an innocent-looking puzzle in the Lady’s and Gentleman’s Diary, a recreational mathematics journal: “Fifteen young ladies in a school walk out three abreast for seven days in succession: it is required to arrange them daily, so that no two shall walk twice abreast.”.

# For Persi Diaconis’ Next Magic Trick …

April 14, 2015 — Persi Diaconis shuffled and cut the deck of cards I’d brought for him, while I promised not to reveal his secrets. “I’m not going to give you the chance,” he retorted. In an empty conference room at the Joint Mathematics Meetings in San Antonio, Texas, this January, he casually tossed the cards into four piles in a seemingly random motion — yet when he checked, each pile magically had an ace on top.

March 12, 2015 — In 1978, the mathematician John McKay noticed what seemed like an odd coincidence. He had been studying the different ways of representing the structure of a mysterious entity called the monster group, a gargantuan algebraic object that, mathematicians believed, captured a new kind of symmetry. Mathematicians weren’t sure that the monster group actually existed, but they knew that if it did exist, it acted in special ways in particular dimensions, the first two of which were 1 and 196,883.

### Erica Klarreich

I have been writing about mathematics and science for a popular audience for more than fifteen years. A mathematician before I became a full-time journalist, I try to convey the essence of complex mathematical ideas to non-mathematicians, and give them a sense of the beauty and depth of mathematics.

I also enjoy plunging into topics far from my mathematical roots, and have written about fields such as economics, computer science, medicine, and biology — often as these fields relate to mathematics, but often simply for their own sake.

As a freelance journalist based in Berkeley, California, I have written for many publications, including Nature, Quanta Magazine, ScientificAmerican.com, New Scientist, American Scientist, Wired.com, Nautilus, and Science News, for which I was the mathematics correspondent for several years. I was also the Journalist in Residence at the Mathematical Sciences Research Institute in Berkeley. My work has been reprinted in the 2010, 2011, and 2016 volumes of "The Best Writing on Mathematics."

I am a graduate of the science writing program at the University of California, Santa Cruz, and I have a Ph.D. in mathematics from Stony Brook University.

For the Fall 2016 semester, I am the Journalist in Residence at the Simons Institute for the Theory of Computing at the University of California, Berkeley.

Contact me at klarreic@nasw.org.