Unpuzzled by the Challenge, the New IBM Puzzle Master is Ready for Action

By Katia Moskvitch

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In the 100 prisoners problem, each prisoner has to find a specific number in one of 100 drawers, but is allowed to open only 50 of the drawers.

Imagine a room with 100 boxes, each with a number between 1 and 100. Alice enters the room; she can switch the numbers between exactly one pair of boxes, if she wishes to do so. Then she leaves, all the boxes are closed, and Bob enters. Although Bob could speak to Alice before she had gone into the room, they have no further contact. Now Bob is given a random number between 1 and 100 and has to find the box with that number. He can open at most 50 boxes. What strategy guarantees he’ll succeed?

Tricky? You bet! To know if your answer is right, you better contact IBM Research’s new Puzzle Master. Yes, there is such a title — and it belongs to Gadi Aleksandrowicz, a mathematics whiz and quantum computing scientist at IBM Research, Haifa. He has just taken over the Puzzle Master role from Oded Margalit, who held it for 13 years.

Not puzzled by the new challenge in the slightest, Aleksandrowicz is eager and ready to tickle the brainwaves of anyone willing to solve mathematical riddles just for fun. From now on, he’ll be managing the IBM puzzle page, Ponder This, and will publish his first challenge at the end of June. He’ll also continue to share his passion for puzzles on his popular personal blog (in Hebrew) and through his math lectures at the Technion, Israel Institute of Technology.

Ponder This initiative started in May 1998, originally aimed at boosting IBM scientists’ productivity. The idea was to help them get unstuck if they faced a challenge in their work-related research by deflecting attention to an entirely different type of problem. With more and more employees sharing math riddles, the company eventually began publishing them online, open to all.

IBM researcher Don Coppersmith became the first official Puzzle Master, in May 1998. James B. Shearer succeeded him in 2005, and in 2007, Margalit. And now, Aleksandrowicz.

With time, puzzles have become more and more elaborate and ambitious. The solution is typically posted a month after the challenge itself; occasionally, the Puzzle Master leaves the challenge up for longer when the riddle is too hard. Try the June puzzle — it’s the last one designed by Margalit. He dedicated it to his successor.

The Master lists online the names of those who solve the riddle correctly, regularly updating the list. While it may take weeks to find a solution, in the end, Aleksandrowicz says, it must be simple. “If the solution is complex, this is a research question, not a puzzle,” he smiles.

A good puzzle appeals to your knowledge, he adds, making you use familiar tools and methods of thinking in ways you don’t usually use. “A good puzzle should be extremely clear and simple to understand, without any language tricks that obscure the true meaning of the riddle,” he says.

While Aleksandrowicz is new to Ponder This, he has been at IBM for eight years. In his regular job, he uses complex mathematics to build methods that characterize, verify, and try to suppress external disturbances (in science speak, ‘noise’) in quantum computers. Noise is the Achilles heel of this emerging technology — making the noise as low as possible should greatly improve the quality of qubits, the basic units of quantum information that make quantum computers work.

Aleksandrowicz wants to inject some quantum into his riddles, too. “This is one of the directions I’m going to think about when designing new puzzles,” he says. “Quantum is an interesting world and we have interesting mathematical opportunities there. One of the nice things about quantum is that it’s very eclectic, and questions come from all sorts of directions.”

But his puzzles won’t be just about quantum. “Quantum is very nice mathematics, but it’s also a very specific type of mathematics. And I don’t want to be focusing only on quantum,” he says. “After all, mathematics in general presents a challenge, a discovery. You have to understand the conditions, what happens if they change and why they exist. Your thinking has to be active all the time. That’s my motto on how to approach everything — you have to be an active thinker.”

The Ponder This site has an average of 10,000 monthly visitors and hundreds of solvers around the globe. Not all puzzles are just games — some are helpful at modeling business problems. For instance, in May 2018, Margalit aimed a challenge at finance experts: “We have 11 coins, and exactly two of them are counterfeit with slightly smaller weights than the others. Find the two fake coins using a double-pan balance scale just four times.”

In April, Margalit decided to design a challenge about the ongoing COVID-19 pandemic. He drew a square with a triangle on top, with the summits representing five cities connected to one another. “Assume that the infection passes daily along the edges,” wrote Margalit. “Find a graph with no more than eight vertices that gives a probability of 70 percent of all cities being infected after ten days.”

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Ponder This: April 2020 Challenge

And May’s puzzle honored the mathematical genius John Horton Conway, who passed away on April 11, 2020. Conway researched many topics in mathematics, and one of his most famous inventions was the Game of Life. In the standard game, each cell has eight neighbors; in Margalit’s puzzle — just four (meaning only those cells with adjacent edges).

“The standard rules can be formulated as 000100000;001100000 — if the cell is empty, it is born if it has exactly three live neighbors; if the cell is alive, it stays alive if it has two or three live neighbors. In our version of the game, the rules 01100;00010 mean that a cell is born if it has one or two neighbors and stays alive if it has three. If we start with a single cell in the middle of an 11x11 torus board, then after 15 generations, you will have an alternating chess-like pattern, and after 16 steps, just the four corners. Your task, this month, is to find rules for our version of the game and an initial input on an 11x11 torus board that will lead, after at least 100,000 generations, to a 72-long cycle.” Wow. My mind is blown.

Aleksandrowicz hasn’t yet published his first puzzle, for July, but it’s imminent. So stay tuned — after all, as the Hungarian mathematician George Polya once said, “a great discovery solves a great problem, but there is a grain of discovery in the solution of any problem.” This quote, says the brand-new Puzzle Master, represents his own thoughts on the way people should approach everything — from mathematics to the life itself.

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This is the official Medium account of IBM Research. It’s managed by IBM Research’s Chief Writer Katia Moskvitch & follows the IBM Social Computing Guidelines.

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