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Mark Nelson

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UCLA Wins Mersenne Lottery

September 29, 2008

Computational feats are not normally the kind of thing mentioned in the mainstream press, but the discovery of the 43rd Mersenne prime was big enough for even the LA Times to cover.

Of course, this feat comes with a $100,000 prize from the Electronic Frontier Foundation, which makes the story a bit spicier. Everyone likes to hear about the latest lottery winner.

How They Did It

Edson Smith is the Computing Resource Manager in the Math department at UCLA, and he is credited with leading their succesful effort.  I asked Edson about the setup used to find the newest Mersenne:

Our department actually has a large traditional Beowulf cluster running Linux on top of generic hardware.  We use this cluster for research in Applied Mathematics.

However, for the Mersenne Prime software, the situation was different.  The 75 XP machines involved are desktop boxes, and used by undergraduate students for learning programming and running math analysis software.  Since the lab isn't open at night, these machines have lots of idle CPU cycles, which makes them a natural to run CPU-intensive background jobs like Prime95, the Mersenne factoring program.

If only Microsoft wasn't in the process of orphaning XP they could have used this for some great PR. Maybe even have Jerry and Bill explain exactly what a prime number is.

A Bit of Luck

Some of the press articles make it sound as though this was a concerted effort by the UCLA math department, but Edson also dispels that notion:

We never expected to find a Mersenne Prime (stated odds are 150,000 to 1 against).  Rather, we thought this would be a good project that would get undergraduates in our Program In Computing courses (most of whom are not Computer Science or Math majors) interested in Computational Mathematics.

That's pretty much the definition of serendipity: a demonstration project turns into a nice mathematical find with a hefty cash prize attached to it.

Reference Material

Edson has created a nice FAQ regarding this discovery. The actual value of the prime is 243112609 - 1, and you can see all 12 million plus digits here.The GIMPS software used to find the prime employs a program called Prime95. You can get source versions of Prime95 here. And if the notion of picking up a few bucks for finding new primes is attractive, read about the ongoing EFF prizes here .



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