Mathblogging.orgRecent Postshttp://www.mathblogging.org/scripts/feed.php20141024T10:39:4204:00No copyright asserted over individual posts; see original posts for copyright and/or licensing.Mathblogging.org Atom serializer5102http://www.mathblogging.org/post/10222720141024T03:00:0004:00Mathematical Association of America5102 = 2 x 2551.<br /><br />5102 is a semiprime whose digit sum is a perfect cube (A245021).<br /><br />5102 divides 516  1.<br /><br />5102 is 6888 in base 9 (A043487).<br /><br /><br />Source: OEISSignshttp://www.mathblogging.org/post/10222620141024T01:00:0004:00(x, why?)(Click on the comic if you can't see the full image.)<br /> (C)Copyright 2014, C. Burke.Happy 7th Birthday, (x, why?)! Back? After seven years and 921 comics (more or less), I'm not going anywhere! Funny thing about using song lyrics. Thanks to the Internet I can check on the lyrics I'm not sure about, and discover that the ones I've "known" since I was a kid aren't actually the words, but they've been stored that way. As for "Signs", I discovered that every site had one of two distinct sets of
[…]Weird things Peruvians dohttp://www.mathblogging.org/post/10222520141024T00:04:3704:00anngorsuchToo many funny things have happened this week to go unmentioned (and also I still haven’t had time to write out a long post about what I’ve been up) so here is a list of “weird” things about Perú.” This … Continue reading →An Alternative to the SeddighinHajiaghayi Ranking Methodologyhttp://www.mathblogging.org/post/10222420141023T23:53:1904:00lucaSaeed Seddighin and MohammadTaghi Hajiaghayi have proposed a ranking methodology for theory groups based on the following desiderata: (1) the ranking should be objective, and based only on quantitative information and (2) the ranking should be transparent, and the methodology openly revealed. Inspired by their work, I propose an alternative methodology that meets both criteria, […]Is the twoBurke ballot the new butterfly ballot?http://www.mathblogging.org/post/10222220141023T23:42:1104:00JSEScott Walker’s opponent takes on the WEDC: BURKE: One other area outside of that that people really should take a look at is the Wisconsin Economic Development Corporation, which was a nonprofit, publicprivate corporation created in 2011 which Governor Walker used to make himself the chair of. What’s most interesting is that Governor Walker’s experience […]The PhotoMath App is Good, and History Says Its Here to Stayhttp://www.mathblogging.org/post/10222320141023T23:25:0004:00Chuck BakerIn case you haven't heard about it yet, there is a new education app for iOS and Windows Phone devices called PhotoMath. Most basically, the app utilizes the camera on your device to recognize numbers and letters, runs an algorithm, and then displays a solution on the screen. From there you can follow the solution it generated stepbystep.
Here it is in action.
There are two ways toThe Twordhttp://www.mathblogging.org/post/10222120141023T22:29:2404:00mathgrrlTape. It is not allowed. Origami models are traditionally made with one piece of paper (see Robert Lang‘s site for some amazing examples) that is only folded – never glued, taped, or cut. Modular origami follows the same rules – no glue,… Continue reading →Octobre, 4ème défihttp://www.mathblogging.org/post/10222020141023T22:00:0004:00Ana RechtmanChaque semaine, un défi du calendrier mathématique 2014...

Défis du Calendrier Mathématique 2014
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Carrouselintothecontinuum:
(click through the images to view in...http://www.mathblogging.org/post/10221820141023T21:53:2204:00Unknown<br/> <br/><br/> <br/><br/> <br/><br/> <br/><br/> <br/><br/> <br/><br/> <br/><br/> <br/>intothecontinuum:
(click through the images to view in highres)
Penrose tilings are an example of the nonperiodic tilings discussed in the last post. Recall that these are tilings that cover the entire infinite plane leaving neither gaps nor overlaps. Whats nice about these tilings is that the set of tiles used to construct the Penrose tilings only consists of two different basic shapes consisting of quadrilaterals.
Whats even more remarkable about Penrose tilings is that using just
[…]Domino’s and Linear Equationshttp://www.mathblogging.org/post/10221720141023T21:42:3904:00dkane47I taught the Mathalicious Domino Effect lesson today. It was awesome. First, the lesson is free. Check it out here! I’m in the middle of a unit on linear equations, but it could be used as an intro with same basic background knowledge just as well. The lesson: The lesson has three main parts. First, it gives […]Plate Tectonics – Group preAssessmenthttp://www.mathblogging.org/post/10221920141023T21:33:4804:00Frank McGowanToday, I’ve gone fishing. Next week my 7th grade science classes will shift their focus to geology. Personally, I’m rather excited about the topic and ready to get talking about the movements of the earth. But…what are my students bringing with … Continue reading →10/23/14: Packed House at Math Club!http://www.mathblogging.org/post/10221620141023T21:17:0004:00Robin NehilaToday was a day of mixed emotions. My homeroom students are a very challenging bunch. Today due to certain situations they were even extra hard to deal with. I felt really bad for them. They take FOREVER at their lockers and have been doing really well, but today they just couldn't get it together before recess./lunch and it took them a full 15 minutes to get done. I was livid. I needed to get to study hall to help kids that actually wanted to be there other than […]Pumpkins, Ghosts, Paper Clips, Barbies, and Flowershttp://www.mathblogging.org/post/10221420141023T19:41:0004:00JFairbanksI have a couple of review activities, fun for this time of year, a Dan Meyer activity and some flowers.<br /><br />These are not original ideas and I have blogged about them before.<br /><br />Ghosts in the Graveyard: I took 12 problems and put them onto worksheets so that each team member is working on a problem and then checking with me. If they get it correct, they get a ghost and can tape it to the board in one of four places around town. They don't have their points assigned yet, so they […]A Time When I Directly Toldhttp://www.mathblogging.org/post/10221220141023T19:13:0004:00Michael Pershan<br />We’re studying data in my third grade class. My students as a whole came in with vague notions of the meaning of data (“it’s information”) and some kids were confused as to what this all has to do with math anyway. On an initial dataset, kids mostly categorized things by their superficial features (“restaurants go together”) instead of grouping data more purposely in order to answer particular questions. Their descriptive language was mostly limited to “most” and “least”, […]On This Day in Math  October 24http://www.mathblogging.org/post/10221320141023T19:00:0004:00Pat BallewMonument to Gauss and Weber in Gottingen<br /> Now it is quite clear to me that there are no solid spheres in the heavens, and those that have been devised by authors to save the appearances, exist only in their imagination, for the purpose of permitting the mind to conceive the motion which the heavenly bodies trace in their courses.<br />~Tycho Brahe<br /><br />The 297th day of the year; 2972 = 88209 and 88+209 = 297. (Numbers that have this property are a type of Kaprekar number; there are only three such numbers […]Fraction Remix...http://www.mathblogging.org/post/10221120141023T18:49:0004:00Shireen DadmehrI had about 20 minutes after a test today, and RIGHT before the test, a high school student in precalculus was confused about how to divide 2 fractions, and she couldn't remember the method: "do you multiply the top and bottom?" were words that came out of her mouth.<br /><br />So. I thought I'd give the following short lesson on why the "flip and multiply" that they seem to spout works.<br /><br />First I asked them the following questions:<br /><br />Simplify: (7/3) / (4/5)<br /><br />Then after they did that and checked, I asked
[…]g(Math) for Forms has launched!!http://www.mathblogging.org/post/10221020141023T18:37:0004:00John McGowanI am proud to announce that after months of work and some great advice from the Addon team in NYC, g(Math) for Forms is part of the Google Forms Addon launch! g(Math) for Forms can do everything its Docs and Sheets sistren (or brethren depending on how you feel about g(Math)) can. It can create math expressions, graphs, and statistical displays and insert them directly into your Google Form! <br />Check it out
[…]Feller’s shoes and Rasmus’ socks [well, Karl's actually...]http://www.mathblogging.org/post/10220920141023T18:14:0904:00xi'anYesterday, Rasmus Bååth [of puppies' fame!] posted a very nice blog using ABC to derive the posterior distribution of the total number of socks in the laundry when only pulling out orphan socks and no pair at all in the first eleven draws. Maybe not the most pressing issue for Bayesian inference in the era […]Monotonic bijection from naturals to pairs of natural numbershttp://www.mathblogging.org/post/10220720141023T17:54:0304:00beni22sofThis is a cute problem I found this evening. Suppose is a bijection such that if and , then . Prove that if then . Proof: The trick is to divide the pairs of positive integers into families with the same product. Note that the th column contains as many elements as the number of […]What's it like to create new Mathematics?http://www.mathblogging.org/post/10220820141023T17:43:0004:00Ken AbbottWhat's it like to create new Mathematics?<br><br> Let's create a mathematical object that's an ordered list of two integers..<br /><br /> (a,b) <br /><br /> where a and b are integers. Order is important, so (a,b) and (b,a) are different objects.<br /><br /> Of course, these objects are not much use unless we have some operations we can do with them.<br /><br /> So let's define a multiply operation as follows..<br /><br /> (a,b)*(c,d)=(a*c,b*d)<br /><br /> Here's an example: (3,4)*(2,5)=(3*2,4*5)=(6,20)<br /><br /> This is interesting (1,1)*(a,b)=(a,b) <br /><br /> So the object (1,1) plays the</br>
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[…]algebraic structure of integers together with addition and multiplication proofhttp://www.mathblogging.org/post/10220520141023T16:25:2204:00Unknownnewest proofHomehttp://www.mathblogging.org/post/10220620141023T16:17:3004:00RichardZach
Courses
Logic I (Phil 279)
Logic II (Phil 379)
Logic III (Phil 479)
Modal Logic (Phil 579.2/679.5)
Nineteenth and Twentieth Century Analytic Philosophy (Phil 307)
[…]Three filtrations on the Grothendieck ring of a schemehttp://www.mathblogging.org/post/10220420141023T15:45:0104:00pbelmansToday’s blog post is inspired by the Chern classes seminar that we are conducting, but it takes a rather big leap from where I left off. Everything I say is based on SGA6 and Fulton–Lang’s Riemann–Roch algebra (which is a true gem I discovered). The lambdaring associated to a scheme If you have a sufficiently […]the distributivity law for natural numbers%2Fproof by inductionhttp://www.mathblogging.org/post/10220320141023T15:40:1004:00Unknownnewest proofFusion Energy: Hope or Hype?http://www.mathblogging.org/post/10220120141023T15:26:5504:00Jonathan M. BorweinIt was with great interest that we read this week of two claimed breakthroughs in the area of fusion energy, by the U.S. aerospace company Lockheed Martin and a separate team of Italian and Swedish scientists. We will continue to monitor both of these developments.Volume and Minecrafthttp://www.mathblogging.org/post/10220220141023T15:23:1604:00mathmindsblogWe continued our work today reasoning about a prism’s dimensions when a volume is doubled. Instead of using our unit cubes, I thought the blocks in Minecraft would work and give students a visual of what is happening to the dimensions when we make a prism twice as big. I first asked them to build […]Puzzlehttp://www.mathblogging.org/post/10220020141023T14:22:0004:00Vlad AlexeevPuzzle
by Jonathan Escobar (highondopamine)
http://impossible.info/english/art/various/jonathanescobar.html
Author  http://highondopamine.deviantart.com/
Frankl, My Dear : 5http://www.mathblogging.org/post/10219820141023T14:00:0704:00Jon AwbreyRe: Dick Lipton & Ken Regan • (1) • (2) Putting all thought of the Frankl Conjecture out of our minds for the moment, let’s return to the proposition in Example 1 and work through its differential analysis from scratch. Example … Continue reading →LearningCentered Classroomshttp://www.mathblogging.org/post/10219920141023T13:54:0004:00Andrew StadelWhat are elements of our classrooms that are studentcentered?<br />What are elements of our classrooms that are teachercentered?<br /><br />InstructionEnvironmentActivitiesAssessmentsCollaborationError analysisSummariesCreationOther<br />Pick any one of the above elements or create your own and go through the images below.<br />*Note how the size of the circles change.<br /><br />Which would best describe your current status?Would you want that to shift? If so, why? How?What would that look like when making a
[…]An Old Class Photohttp://www.mathblogging.org/post/10219520141023T13:42:2404:00mathscinotesOne of my favorite old movies is the “The African Queen” with Humphrey Bogart (he played Charlie) and Katherine Hepburn (she played Rose). In that movie, Rose asks Charlie “Could you make a torpedo?” and Charlie responds: “A torpedo?…You don’t … Continue reading →