User adrian petrescu - MathOverflowmost recent 30 from http://mathoverflow.net2013-05-19T08:22:23Zhttp://mathoverflow.net/feeds/user/817http://www.creativecommons.org/licenses/by-nc/2.5/rdfhttp://mathoverflow.net/questions/761/undergraduate-level-math-books/9445#9445Answer by Adrian Petrescu for Undergraduate Level Math BooksAdrian Petrescu2009-12-20T22:39:55Z2011-05-10T23:02:38Z<p>I liked <a href="http://books.google.ca/books?id=bj1kOY8gOfcC&dq=elements+of+abstract+algebra&printsec=frontcover&source=bl&ots=sMDMivxMQ6&sig=5XAar4HPSaqw0XRPBwt0Om4ibhA&hl=en&ei=SKcuS4fEJsbilAePleCkBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAoQ6AEwAA#v=onepage&q=&f=false" rel="nofollow">Elements of Abstract Algebra</a> by Allan Clark, which is mainly a problem book with a moderate amount of exposition, but the problems are so well-chosen that a diligent undergraduate student working through all of them will come out with a solid knowledge of group theory, classical ring theory, and Galois theory.</p>
http://mathoverflow.net/questions/31879/are-there-other-nice-math-books-close-to-the-style-of-tristan-needham/32211#32211Answer by Adrian Petrescu for Are there other nice math books close to the style of Tristan Needham?Adrian Petrescu2010-07-16T17:53:24Z2010-07-16T17:53:24Z<p>It's not exactly as visual as <em>Visual Complex Analysis</em>, but Michael Spivak's <a href="http://www.amazon.com/Comprehensive-Introduction-Differential-Geometry-Vol/dp/0914098705/ref=pd_sim_b_1" rel="nofollow">A Comprehensive Introduction to Differential Geometry</a> has a lot of the same appeal to intuition and conversational style. (Well, I've only read Volume 1, there's a total of 5, but if they're anything like other Spivak books I've read, this holds true of them as well).</p>
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<p><img src="http://ec1.images-amazon.com/images/G/01/ciu/0b/84/b820d250fca05ed75ca26010.L.jpg" alt="Cover of Volume 1"></p>
http://mathoverflow.net/questions/14574/your-favorite-surprising-connections-in-mathematics/14617#14617Answer by Adrian Petrescu for Your favorite surprising connections in MathematicsAdrian Petrescu2010-02-08T07:09:07Z2010-02-16T23:55:09Z<p>This is probably not the most serious of applications, but I found the equivalence (in game theory) of the determinacy of Nash's board game Hex with the Brouwer Fixed Point theorem to be a surprising, if somewhat lighthearted, connection.</p>
<p>You can read <a href="http://www.jstor.org/pss/2320146" rel="nofollow">David Gale's paper</a>.</p>
http://mathoverflow.net/questions/9218/probabilistic-proofs-of-analytic-facts/9252#9252Answer by Adrian Petrescu for Probabilistic Proofs of Analytic FactsAdrian Petrescu2009-12-18T07:40:32Z2009-12-18T07:40:32Z<p><a href="http://www.jstor.org/pss/2318544" rel="nofollow">This paper</a> (Prime Numbers and Brownian Motion, by Patrick Billingsley) is perhaps more about proving number theoretic facts than analytical, but at least to me they have a very analytical flavor anyway, and was the first thing to come into my mind when I read your question. I think you would find it interesting.</p>
http://mathoverflow.net/questions/5145/completeness-under-uniform-continuity"Completeness" under uniform continuityAdrian Petrescu2009-11-12T03:28:59Z2009-11-12T03:28:59Z
<p>We say that a metric space where every convergent sequence converges to something in the space is called "complete" and has useful properties, but is there a specific name for spaces which fail to be complete, but have at least the condition that every <strong>uniformly</strong> convergent sequence converges to something in the space?</p>
<p>Like, for instance, the metric space of polynomials over R is not complete as far as I know, but if you restrict yourself to uniformly convergent sequences, then you always get a polynomial. Is there a name for that, or are these types of spaces just not that interesting?</p>
http://mathoverflow.net/questions/7330/which-math-paper-maximizes-the-ratio-importance-length/7891#7891Comment by Adrian PetrescuAdrian Petrescu2011-10-30T05:25:01Z2011-10-30T05:25:01ZLink: <a href="http://courses.engr.illinois.edu/ece586/TB/Nash-NAS-1950.pdf" rel="nofollow">courses.engr.illinois.edu/ece586/TB/…</a>http://mathoverflow.net/questions/48477/never-appeared-forthcoming-papers/48533#48533Comment by Adrian PetrescuAdrian Petrescu2010-12-07T06:24:25Z2010-12-07T06:24:25ZAccording to Knuth, 4A was completed and sent to the printer today (December 6th, 2010)http://mathoverflow.net/questions/20430/is-there-an-explicit-example-of-a-complex-number-which-is-not-a-period/20435#20435Comment by Adrian PetrescuAdrian Petrescu2010-09-08T06:50:29Z2010-09-08T06:50:29ZFrom the abstract: "In particular we prove that periods can be effectively approximated by elementary rational Cauchy sequences. As an application, we exhibit a computable real number which is not a period." So it definitely does have other importance; it probably just pops out a construction of a non-period as an easy corollary or something.http://mathoverflow.net/questions/35677/binary-decimal-expansion-of-algebraic-numbersComment by Adrian PetrescuAdrian Petrescu2010-08-15T18:24:02Z2010-08-15T18:24:02ZDepending on the answers you get, this may turn out to be MO-suitable. In case it's not, however, the other "better" math forum for it would be <a href="http://math.stackexchange.com/" rel="nofollow">math.stackexchange.com</a>.http://mathoverflow.net/questions/33402/how-to-test-if-the-difference-between-probabilities-is-statistically-significantComment by Adrian PetrescuAdrian Petrescu2010-07-26T14:46:18Z2010-07-26T14:46:18ZIn about 4 hours, a new Stack Exchange site focusing on statistics will become public: <a href="http://stats.stackexchange.com/" rel="nofollow">stats.stackexchange.com</a> I think your question will be better-suited there.http://mathoverflow.net/questions/30511/ebook-readers-for-mathematics/30520#30520Comment by Adrian PetrescuAdrian Petrescu2010-07-04T17:44:57Z2010-07-04T17:44:57ZIt should also be mentioned that the latest software update for the Kindle, 2.5.3, now allows zooming of PDFs, which makes it even more useful especially for PDFs that have two pages scanned per the same image.
I use it for reading textbooks and papers all the time and it is a very comfortable experience.http://mathoverflow.net/questions/5145/completeness-under-uniform-continuityComment by Adrian PetrescuAdrian Petrescu2009-11-12T03:38:06Z2009-11-12T03:38:06ZI could be misunderstanding, but I'm not saying that the polynomials themselves are uniformly convergent, rather that the SEQUENCE of polynomials converges uniformly (to another polynomial) under the usual metric.
Does this clear it up?