Charles Weibel's Home Page

  • The 40th Almgren "Mayday" Race will be held on Sunday May 3, 2015.
    It will start at Landing Lane (Rutgers) and end at Alexander Road in Princeton.

    Teaching Stuff (for more information, see Rutgers University, the Rutgers Math Department, and its Graduate Math Program.

    Definition: Proofiness is defined as "the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it's not." -Charles Seife

    Research papers & stuff: This is a link to some of my research papers. Here are my research interests and my Ph.D. Students.

    Do you like the History of Mathematics? Here are some articles: I am often busy editing the Journal of Pure and Applied Algebra (JPAA), the Annals of K-theory, the Journal of K-theory and the journals HHA and JHRS.
    Seminars I like:

    Links to other WWW sites
    Fun Question: How can you prove that 123456789098765432111 is a prime number?
    note that 12345678987654321 = 111111111 x 111111111
    Fun Facts about Mersenne primes: In 1644, a French monk named Marin Mersenne studied numbers of the form N=2p-1, where p is prime, and published a list of 11 such numbers he claimed were prime numbers (he got two wrong). Such prime numbers are called Mersenne primes. The first few Mersenne primes (p=2,3,5,7) are 3,7,31,127, but p=11 gives the non-prime 2047=23*89 (as was discovered in 1536 by Regius).
    Not all numbers of the form 2p-1 are prime, as Regius' example 2047 (p=11) shows. The next few primes for which 2p-1 is not prime are p=23 and p=37 (discovered by Fermat in 1640), and p=29 (discovered by Euler in 1738).

    Mersenne primes are the largest primes we know. In 2011, the list of the first 41 Mersenne primes was verified; we don't know what is the 42nd smallest, even though a handful of larger Mersenne primes are known. For years, the Electronic Frontier Foundation (EFF) offered a $50,000 prize for the first known prime with over 10 million digits. The race to win this prize came down the wire in Summer 2008, as the 45th and 46th known Mersenne primes were discovered in within 2 weeks of each other by the UCLA Math Department (who won the prize) and an Electrical Engineer in Germany, respectively. The largest is the 45th, which has 13 million digits and p=43,112,609; the 46th has 11 million digits.
    (Each prime N=2p-1 has p log10(2) digits.)
    More recently, the 47th known Mersenne prime was discovered in April 2009 by a Norwegian named Odd Magner Stridmo, with p=42,643,801. Surprisingly, it is slightly smaller (by 141,000 digits) than the 45th Mersenne prime. For more information, check out the Mersenne site.
    Charles Weibel / weibel @ / January 31, 2015

    MATHJAX test: $\partial y/\partial t=\partial y/\partial x$, $\sqrt2=1.4141$,      $\forall n\in\mathbb{N}, e^n\in \mathbb R$
    If $f(t)=\int_t^1 dx/x$ then $f(t)\to\infty$ as $t\to\infty$

    HTML 4 font rednering:   ∂y/∂t = ∂y/∂x   √2 =1.414
    If f(t)= ∫t 1 dx/x then f(t) → ∞ as t → 0. This really means:   (∀ε ∈ℝ,  ε>0) (∃δ>0) f(δ) > 1/ε .
    ℕ (natural numbers), ℤ (integers), ℚ (rationals), ℝ (reals), ℂ (complexes)
    The ndash (–) is & #150; ,   & #8211; and & ndash; !   I prefer the longer —, which is & mdash; or & #151;.