Category Archives: News

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Work with the Polymath project was featured by Notices of the AMS

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Category : News , Projects

Notices of the American Mathematical SocietyThe Polymath8 participants was featured on the June/July cover of Notices of the American Mathematical Society, the world’s most widely read mathematical journal.

The photographs on the cover portray thirteen of the fifteen people, including a team of top mathematicians, as being primary participants of the Polymath8 project that improved dramatically the bound of prime gaps, based on the stunning work of  Dr. Yitang Zhang.

Read more at Notices of the AMS.


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Work with the Polymath project was published on Algebra & Number Theory

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The work with the Polymath project was published on Algebra & Number Theory.

Abstract: We prove distribution estimates for primes in arithmetic progressions to large smooth squarefree moduli, with respect to congruence classes obeying Chinese remainder theorem conditions, obtaining an exponent of distribution 1/2+7/300.


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Work with the Polymath project was published on Research in the Mathematical Sciences

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The work with the Polymath project was published on Research in the Mathematical Sciences.

Here is the list of Polymath8b authors (arranged in alphabetical order of surname): Ignace Bogaert, Aubrey de Grey, Gergely Harcos, Emmanuel Kowalski, Philippe Michel, James Maynard, Paul Nelson, Pace Nielsen, Eytan Paldi, Andrew V. Sutherland, Terence Tao, Xiao-Feng Xie

Abstract: For any m \geq 1, let H_m denote the quantity \liminf_{n \to \infty} (p_{n+m}-p_n), where p_n is the n^{\text{th}} prime. A celebrated recent result of Zhang showed the finiteness of H_1, with the explicit bound H_1 \leq 70000000. This was then improved by us (the Polymath8 project) to H_1 \leq 4680, and then by Maynard to H_1 \leq 600, who also established for the first time a finiteness result for H_m for m \geq 2, and specifically that H_m \ll m^3 e^{4m}. If one also assumes the Elliott-Halberstam conjecture, Maynard obtained the bound H_1 \leq 12, improving upon the previous bound H_1 \leq 16 of Goldston, Pintz, and Y{\i}ld{\i}r{\i}m, as well as the bound H_m \ll m^3 e^{2m}. In this paper, we extend the methods of Maynard by generalizing the Selberg sieve further, and by performing more extensive numerical calculations. As a consequence, we can obtain the bound H_1 \leq 246 unconditionally, and H_1 \leq 6 under the assumption of the generalized Elliott-Halberstam conjecture. Indeed, under the latter conjecture we show the stronger statement that for any admissible triple (h_1,h_2,h_3), there are infinitely many n for which at least two of n+h_1,n+h_2,n+h_3 are prime, and also obtain a related disjunction asserting that either the twin prime conjecture holds, or the even Goldbach conjecture is asymptotically true if one allows an additive error of at most 2, or both. We also modify the “parity problem” argument of Selberg to show that the H_1 \leq 6 bound is the best possible that one can obtain from purely sieve-theoretic considerations. For larger m, we use the distributional results obtained previously by our project to obtain the unconditional asymptotic bound H_m \ll m e^{(4-\frac{28}{157})m}, or H_m \ll m e^{2m} under the assumption of the Elliott-Halberstam conjecture. We also obtain explicit upper bounds for H_m when m=2,3,4,5.


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Smart traffic signals listed as 25 Great Things About Computer Science at Carnegie Mellon University

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The smart and scalable urban traffic control system (invented by Xie, et al.) is listed in 25 Great Things  about Computer Science at Carnegie Mellon University.

What’s so great about computer science at Carnegie Mellon?

We’re glad you asked! Here are 25 great ideas from CMU computer scientists to think about as we celebrate the birthday of the School of Computer Science.

1.    Artificial intelligence, 1955-56

12. JAVA, 1991

25. Smart, adaptable traffic signals, 2012

       Smart traffic lights developed at CMU’s Robotics Institute are saving time and energy, and cutting down on the amount of air pollution created by idling cars. First rolled out in Pittsburgh’s East Liberty neighborhood, the new signals are being studied around the country.

25 Great Things About SCS


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Work with the Polymath project was reported by Der Spiegel

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Category : News , Projects

This work with the Polymath8 project was to find narrow gaps between primes.

derspiegel

Mal steuerte Xiao-Feng Xie einen Vorschlag bei, ein Robotikexperte aus Pittsburgh. Mal meldete sich Terence Tao aus Los Angeles, den einige für den brillantesten aller lebenden Mathematiker halten. Wieder andere Anregungen kamen von einem Anonymus, der sich nur als v08ltu zu erkennen gab.

Read more at Der Spiegel (web | pdf).


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Solving the Magic Square Problem Using Modern Heuristic Methods

Category : News , Software

Ms_sf_2This problem is to solve the Magic Square Problem (constrained and unconstrained versions), a combinatorial optimization problem, using modern heuristic methods.

Magic squares have been a source of fascination since ancient times, over 4,000 years. A magic square is a square matrix of size n, containing each of the numbers 1 to n2 exactly once, in which each column, each row, and both diagonals add up to the same magic number.

It is possible to impose many different constraints on a standard magic square problem. Here the constrained version stipulates that the solution matrix must have a pre-defined contiguous sub-matrix.

Here is the binary code, and here is the readme file. As the 2nd runner-up, this program solved the constrained version of 400 x 400 magic square within a minute in the 2011 International Optimisation Competition.

  • X. Xie, “Meta-LS Solver for Magic Square Competition,” International Optimisation Competition, 2011. [PDF] [Code] [Bibtex]
    @TechReport{xie2011tr00,
    Title = {Meta-LS Solver for Magic Square Competition},
    Author = {Xiao-Feng Xie},
    Code={http://www.wiomax.com/team/xie/project/magic/MagicSquare.jar},
    PDF={http://www.wiomax.com/team/xie/project/magic/IOC_readme.pdf},
    Institution={International Optimisation Competition},
    Year = {2011}
    }