# Ken Regan Turned 61

*Happy birthday to Ken*

Ken Regan is of course my partner on GLL. He is faculty in the computer science department at the University of Buffalo. His PhD was in 1986 from Oxford University and it was titled *On the separation of complexity classes*. He was the PhD student of Dominic Welsh who was a student of John Hammersley.

Today I would like to wish Ken a happy birthday.

He is now 61 years young. I hope you will join me and wish him many more birthdays. His age is special for many reasons:

- It is a twin prime.
- It is equal to .
- It is the ninth Mersenne prime: .

There are three big **I’s** in his life. Let’s talk about two of them.

## Interest in Cricket

Ken loves sports in general and especially cricket. Last Sunday he told me he watched his Bills win their first NFL game while he watched a cricket match. I have no idea how cricket works, but here is Ken’s explanation: *Are Cricket and Baseball sister games?*

- In a baseball game you see pitchers on the field.

In a cricket match you see fielders on the pitch. - In baseball, a bad delivery is called a “Ball”.

In cricket, it’s a “No Ball”. - In baseball, if a batter carries his bat, he’s out.

In cricket, the batsmen always carry their bat, and an opening batsman who “carries his bat” is never out. - In baseball, an innings is called a half-inning.

In cricket, an inning is called an innings. - In baseball, a batter hit by a pitched ball gets a free pass to First Base.

In cricket, such a batter can be Out Leg Before Wicket. - In baseball, if a ball is caught over the boundary, “yer out!”

In cricket, you score 6 runs. - In baseball, when a batter “walks”, he gets a free pass to first and is not out.

In cricket, it means the batsman declares himself out before the umpire has a chance to make the call. This classic show of sportsmanship is considered unsportsmanlike in baseball.## Interest in Chess

When the chess world wants to know if someone has cheated, they call Ken. He is an international chess master, and has worked on stopping cheating for years. It is important these days, since most tournaments are now online. And cheating is easier when no one is directly able to watch you. Ken is busy.

Let’s look at the cheating problem. Suppose that Alice and Bob are playing an online game of chess. Alice makes her own moves, but she wonders if Bob could be cheating. He could be using advice from another “player”, Sally. There are several points:

- Sally is a stronger player than anyone—she can easily beat Alice and Bob.
- Sally not only says “here is my move”—she will sometimes give several good moves.
- Sally is a program that is deterministic—given a position she gives the same answer.The issue for Ken is: When Alice played Bob did Bob make the moves or did he consult Sally?

There are many complexities:

- What if Bob agreed with all Sally’s moves? Then he certainly did cheat.
- What if Bob was just lucky and played above his strength? Then he did not cheat.
- What if Bob used Sally for some positions but not others? Then he did cheat, but it may be hard to be sure.
- And so on.

What Ken has done is create both a theory and programs to determine whether Bob did indeed cheat. I find the general problem of telling if one cheats online at chess to be fascinating. See us before for more details and also see this.

## Open Problems

Ken is one of the nicest people I know. Hope he has many more birthdays and many more twin primes.

61 is the least noninteresting number.

A slightly belated Happy Birthday, Ken. Thanks for all your hard work on GLL. Go get those chess cheaters!

-Kathryn

Happy Birthday Ken!

Happy Birthday Ken! 🙂

61 is the 18th prime, so …

here is the Riff for 61

and here is the Rote for 61

and here is the Ref for Riffs and Rotes

Me too 61 soon

Happy Birthday Ken!

Hope you will always be at the prime of your life — even when your age is composite (as it will increasingly be).

It’s a 3D age! Happy birthday!

Chess playing computers have moved away from having experts help them and instead just train themselves.

For chess-cheating I am sure its been helpful that Ken is himself and excellent player. But in the future (or maybe now) will it still be helpful?

Ken and Dick are both nice, perhaps to nice, a point I made when I reviewed their book on my blog:

https://blog.computationalcomplexity.org/2014/05/review-of-people-problems-and-proofs-by.html

Suddenly invented the following

scientific papers’ references paradox:

It may be belated, but happy birthday Ken. I am a few primes ahead of you, but they have all been good ones!

Thanks, everyone, for the birthday wishes. It has been a packed two weeks, with more to come. My cricket witticisms date to the 1980s when I played a little around Oxford—I once scored 19 in a college friendly but my next-highest score was 2. I actually learned about the game while having an Indian and a West Indian roommate at Princeton. I wrote up my cricket pages, however, when I was Director of Graduate Studies for UB CSE in 2002–2006. I conceived the idea of a welcome outing for new graduate students to attend a Buffalo Bisons minor-league baseball game downtown.

It may interest those who study the Internet to see that my cricket pages were noticed by Sam Borden of ESPN. They are the reason I was quoted in this ESPN story in June 2019 when the Yankees and Red Sox played a series in London.

Since 61 is my favorite number, I feel I should leave a comment with a couple other facts about 61. For one, 61 is a hexagonal number. Hexagonal numbers are differences of consecutive cubes, and 61 = 5³ − 4³. 61 is also on the diagonal of the Ackermann function: A(3,3) = 61.