Good Math, Bad Math
Finding the fun in good math; Shredding bad math and squashing the crackpots who espouse it.
Friday Random 10, November 14
Hawkwind, "Masters of the Universe": Great bit from the early days of psychadelic/progressive rock. I've got recordings of both the live and the studio versions, and I vastly prefer the studio.Peter Gabriel, "The Family and the Fishing Net&...
~ published: 11/14 at 17:12 ~ permalink
Innumeracy and the U. S. Supreme Court
As long time readers of this blog know, one of the things that drive me crazy - in fact, one of the things that led me to start this blog - is the rampant innumeracy of our society. The vast majority ofAmericans have no real knowledge or comprehension of...
~ published: 11/13 at 15:08 ~ permalink
Evolution Produces Better Antenna; Casey Luskin Very Upset
It's always amusing to wander over to the Discovery Institute's blogs, and see what kind of nonsense they're spouting today. So, today, as I'm feeling like steamed crap, I took a wander over. And what did I find? High grade, low-content rubbish from my o...
~ published: 11/11 at 12:44 ~ permalink
Friday Recipe: Shanghai Xu Chao Mien
(Note: I've changed the transliteration of the name of the dish since the original version of the post. I think it's now the correct pinyin transliteration. Please correct me in the comments if you know, and it's still wrong.) Today you get the recipe for...
~ published: 11/07 at 10:20 ~ permalink
Miscellaneous Post-Election Tidbits
Sorry about the abrupt end to the liveblogging last night; Firefox crashed, and CoverItLive wouldn't let me log back in as the moderator. Anyway, it's a good day to be a liberal. As you all know by now, it was Obama in an absolute landslide. He won by a ...
~ published: 11/05 at 10:44 ~ permalink
LiveBlogging
I'm going to be liveblogging the elections here starting at 7pm. I'll be doing my best to track the results as they come in, and what they mean. Feel free to come join in. Read the comments on this post......
~ published: 11/04 at 16:50 ~ permalink
Reviewing the TMobile G1 - aka the Google Android Phone
Once again, please don't forget about our DonorsChoose drive! Please click in the panel to you left, and go make a donation to help schools get the supplies they need to be able to teach math! Most people must have heard by now that about a week ago, T-m...
~ published: 10/29 at 11:11 ~ permalink
Margin of Error and Election Polls
Before I get to the meat of the post, I want to remind you that our DonorsChoose drive is ending in just a couple of days! A small number of readers have made extremely generous contributions, which is very gratifying. (One person has even taken me up on...
~ published: 10/28 at 20:26 ~ permalink
How Not to Do Message Integrity, featuring CBC-MAC
In my last cryptography post, I wrote about using message authentication codes(MACs) as a way of guaranteeing message integrity. To review briefly, most ciphersare designed to provide message confidentiality - which means that no one but thesender and th...
~ published: 10/24 at 13:21 ~ permalink
Credit Default Swaps: Gambling as Insurance
So, the financial questions keep coming. I'm avoiding a lot of them, because(A) they bore me, and (B) I'm really not the right person to ask. I try to stayout of this stuff unless I have some clue of what I'm talking about. Rest assured, I'm not spending...
~ published: 10/23 at 14:37 ~ permalink
Stupid Economic Comparisons at the New York Times
This is just a short gripe at the NYT, and a featurethat they included in today's Op-Ed section. It purports to compare how the economy does under democratic versusrepublican administrations. They claim that they're computing the returnson a 10,000 doll...
~ published: 10/14 at 15:16 ~ permalink
Infinity is NOT a number
Writing this blog, I get lots of email. One of the things that I get over and over again is a particular kind of cluelessness about the idea of infinity. I get the same basic kind of stupid flames in a lot of different forms: arguments about Cantor's dia...
~ published: 10/13 at 12:00 ~ permalink
Friday Recipe: Stuffed Flank Steak
This is a recipe I created just a couple of weeks ago. I saw a beautiful Angus beef flank steak on sale, and wanted to find something to do with it. I came up with this idea of stuffing it. Amusingly, the day after it, a recipe appeared in the New York T...
~ published: 10/10 at 14:03 ~ permalink
Nobel Prize Blogging: Symmetry Breaking
Today the 2008 Nobel Prize winners were announced for physics. It was given to three physicists who described something called symmetry breaking. Since most people don't know what symmetry breaking is, but people remember me writing about group theory an...
~ published: 10/07 at 19:36 ~ permalink
Cryptographic Integrity using Message Authentication Codes
I don't have a lot of time to write; I'm having my fifth (I think) upper endoscopy done tomorrow, which means that the day's going to be a wash; and Yom Kippur is thursday, and I need to cook, so between the personal crap and work, I'm not going to have ...
~ published: 10/06 at 08:39 ~ permalink
Friday Random Ten, October 3
Don't forget to go and donate some money to schools throughour DonorsChoose challenge. Seriously - throw them a couple of bucks. It doesn't need to be much. There are around three thousand people per day who read this blog; if you each contribute $5, it ...
~ published: 10/03 at 14:27 ~ permalink
Differential Cryptanalysis
Now, we're finally reaching the point where the block-cipher stuff gets really fun: block cryptanalysis. As I've explained before, the key properties of a really goodencryption system are: It's easy to compute the ciphertext given the plaintext and the ...
~ published: 10/02 at 14:07 ~ permalink
ScienceBlogs DonorsChoose Drive 2008
Every year at ScienceBlogs, we do a charity drive for DonorsChoose.org. If you haven't heard of them, DonorsChoose is a charity that takes proposals from schoolteachers, and lets people pick specific proposals to donate money to. We run our charity chal...
~ published: 10/01 at 19:22 ~ permalink
How Mortgages Turned into a Trillion Dollar Disaster
Ok, another batch of questions have come in, all variants onthe same theme. The question is, if mortgages are at the root of the current economic disaster, how can it possibly result in close to a trillion dollars worth of losses? It definitely seems str...
~ published: 09/25 at 18:54 ~ permalink
Bad Probability and Economic Disaster; or How Ignoring Bayes Theorem Caused the Mess
There is at least a little bit of interesting bath mathto learn from in the whole financial mess going on now. A coupleof commenters beat me to it, but I'll go ahead and write aboutit anyway. One of the big questions that comes up again and again is: how...
~ published: 09/23 at 20:41 ~ permalink
Economic Disasters and Stupid Evil People
With the insanity that's been going on in the financial worldlately, a bunch of people have asked me to post a followup to myearlier posts on the whole mortgage disaster, to try to explainwhat's going on lately. As I keep saying when people ask me things...
~ published: 09/22 at 16:39 ~ permalink
Screwing Up Modes of Operation: Counter done right
So, as it turned out, I made a major screwup in my post earlier today on modes of operation. Rather than just edit the post, I'm adding a new post with the corrected description of the counter mode, and a bit of explanation. I figure that if I screw up b...
~ published: 09/15 at 18:23 ~ permalink
Modes of Operation in Block Cryptography
Sorry for the slow pace of the blog lately. I've been sick with a horriblesinus infection for the last month, and I've also been particularly busy with work, which have left me with neither the time nor the energy to do the research necessary to put toge...
~ published: 09/15 at 09:13 ~ permalink
Friday Random 10, Sept 12
My apologies for how slow the blog has been lately. I've been sick with a horriblesinus infection for the last month. I saw an ENT on wednesday, and with massive doses of antibiotics and steroids, I'm finally on the mend, so hopefully things will get bac...
~ published: 09/12 at 19:39 ~ permalink
Suddenly, I feel... coordinated
This is about as off-topic as it gets, but I can't resist posting. Y'see, I'm a spectacularly uncoordinated person. I can trip over nothing. If you throw me a ball, the chances of my being able to catch it are frighteningly low. When I was in high school...
~ published: 09/11 at 07:32 ~ permalink
DES Encryption Part 1: Encrypting the Blocks
As promised, now we're going to look at the first major blockcipher: the DES. DES stands for "data encryption standard"; DES was the first encryption system standardized by the US government for official use. It's an excellent example of a stro...
~ published: 09/08 at 09:11 ~ permalink
Introduction to Block Ciphers
Where encryption starts getting really interesting, in my opinion, isblock ciphers. Block ciphers are a general category of ciphers that are sort of a combination of substitution and transposition ciphers, andsort of something entirely different. They're...
~ published: 09/04 at 14:36 ~ permalink
Friday Random Ten, The Vacation Edition
I was away on vacation this week, which explains the near-totalsilence on the blog. But at least you'll get a FRT from me. And somenice posts on cryptography and game theory coming next week. Gogol Bordello, "Dub the Frequencies of Love": East...
~ published: 08/29 at 15:41 ~ permalink
Transposition Ciphers
The second major family of encryption techniques is called transposition ciphers. I find transposition ciphers to berather dull; in their pure form, they're very simple, and not very difficultto crack, even without computers. But some of the most sophist...
~ published: 08/24 at 18:10 ~ permalink
Friday Random 10, August 22
Solas, "Darkness, Darkness": One of my favorite Irish bands doing a great cover of an old song.A Silver Mt. Zion, "Goodbye Desolate Railyard": a decent ASMZ track, but not an outstanding one.Mogwai, "Acid Food": Anything b...
~ published: 08/22 at 19:50 ~ permalink
Astrology and the Olympics
An alert reader sent me link to a stupidarticle published by Reuters about the Olympics and Astrology. It's a classic kind of crackpot silliness, which I've describedin numerous articles before. It's yet another example of pareidolia - that is, seeing pa...
~ published: 08/22 at 16:42 ~ permalink
The Food Experience Meme
I found a fun meme via Rev. BigDumbChimp, involving food. I'm a sucker for anything involving eating. Venison: Nope. Nettle tea: yes. Didn't like it. Huevos rancheros: Yes, yummy. Steak tartare: nope. Crocodile: Yup. Mediocre. Not a bad flavor, but...
~ published: 08/20 at 13:21 ~ permalink
Why is randomness informative? Correcting the Clueless Creationists
Someone sent me some questions about information theory; or actually,about some questions raised by a bozo creationist arguing about informationtheory. But the issues raised are interesting. So while I'mnominally snarking at a clueless creationist, I'm ...
~ published: 08/18 at 10:17 ~ permalink
Friday Random 10, August 15
One of the things that I always like to talk about is how a natural expression of randomness will periodically produce something that appearsnon-random - and in fact, if it doesn't, then it's not really random! This weeks friday random 10 is a great exam...
~ published: 08/15 at 12:32 ~ permalink
Introducing Cryptanalysis
To understand why serious encryption algorithms are so complex, and why it'sso important to be careful with the critical secrets that make an encryptionsystem work, it's useful to understand something about how people breakencryption systems. The study o...
~ published: 08/15 at 08:01 ~ permalink
Rotating Ciphers
So, last time, we looked at simple substitution ciphers. In a substitutioncipher, you take each letter, and pick a replacement for it. To encrypt amessage, you just substitute the replacement for each instance of each letter.As I explained, it's typicall...
~ published: 08/11 at 13:57 ~ permalink
Simple Encryption: Introduction and Substitution Ciphers
The starting point talking about encryption is to understandwhat the point of it is; what it's supposed to do, what problems it's supposed to avoid. Encryption is fundamentally about communication: you've got two parties who want to communicate, but don'...
~ published: 08/08 at 09:57 ~ permalink
Encryption, Privacy, and You
As you've probably heard, the US customs service has, recently, asserted the right to confiscate any and all computers and/or digital storage carried by anyone crossing the US border. They further assertthe right to demand all passwords, encryption keys,...
~ published: 08/07 at 10:18 ~ permalink
Bad Fundies! Chabad takes on Science.
Someone sent me another stupid Jewish article. It's still not thewonderful relativity denial that I lost, but it's pretty delicious asstupidity goes. This time it comes from Chabad. For those who aren'tfamiliar with it, Chabad is a Chasidic organization,...
~ published: 08/06 at 07:32 ~ permalink
Friday Random Ten, August 1st
Kansas, "Byzantium": an example of why Kansas fans waited so long for Kerry Lofgren to return to the band. The guy's a brilliant songwriter. Even with Walsh's voice clearly aging and suffering from abuse, this is fantanstic stuff.Isis, "W...
~ published: 08/01 at 12:14 ~ permalink
Nonsense Pretending: Probability as a Disguise
Once again, you, my readers, have come through with some really high-grade crackpottery. This one was actually sent to me by its author, but I didn't really look at it until several readers sent me the same link because they thought it was my kind of mat...
~ published: 07/31 at 13:35 ~ permalink
Solving Tic-Tac-Toe: Game Tree Basics
Moving on from simple zero-sum games, there are a bunch of directions in whichwe can go. So far, the games we've looked at are very restrictive. Beyond thezero-sum property, they're built on a set of fundamental properties which ultimatelyreduce to the i...
~ published: 07/30 at 10:38 ~ permalink
Teaching Multiplication: Is it repeated addition?
I've been getting peppered with requests to comment on a recent argument that'sbeen going on about math education, particularly with respect to multiplication.We've got a fairly prominent guy named Keith Devlin ranting that"multiplication is not rep...
~ published: 07/25 at 14:01 ~ permalink
Numeric Pareidolia and God in Π
There's one kind of semi-mathematical crackpottery that people frequently send to me, but which i generally don't write about. Given my background, I call it gematria - but it covers a much wider range than what's really technically meant by that term. An...
~ published: 07/24 at 11:33 ~ permalink
Utility Functions
Before we move beyond zero-sum games, it's worth taking a deeper lookat the idea of utilities. As I mentioned before, in a game, the scores inthe matrix are given by something called a utility function. Utility is an idea for how to mathematically descri...
~ published: 07/21 at 10:55 ~ permalink
Friday Random Ten, July 18
The Flower Kings, "Underdog": a neo-progressive track with the lead played by a bagpipe and a steel guitar. How can you not love that?Broken Social Scene, "Ibi Dreams of a Pavement": A post-rock track with vocals. Very good stuff - v...
~ published: 07/18 at 14:07 ~ permalink
Back to Math: Solving Zero-Sum Games
When I last wrote about game theory, we were working up to how to findthe general solution to an iterated two-player zero-sum game. Since it's beena while, I'll take a moment and refresh your memory a bit. A zero-sum game is described as a matrix. One pl...
~ published: 07/16 at 10:13 ~ permalink
Sizzle: A Review of the latest from Randy Olsen
Back in May, we here at ScienceBlogs got an offer to get an advance screener copy of Randy Olson's new movie, "Sizzle", if we promised to review it. I hadn't seen any of Olson's movies before, but I've been involved in a few discussions with h...
~ published: 07/15 at 05:00 ~ permalink
The PZ Cracker Mess
So my fellow SBer PZ is in all sorts of hot water with Catholics over a blog post. I didn't really want to poke my nose into this, but there's been so much noise about it, that it's really unavoidable. But I think I've got a rather different opinion on ...
~ published: 07/14 at 13:08 ~ permalink
B-Trees - Balanced Search Trees for Slow Storage
Another cool, but frequently overlooked, data structure in the tree family is called the B-tree. A B-tree is a search tree, very similar to a BST in concept, but optimized differently. BSTs provide logarithmic time operations, where the performanceis fun...
~ published: 07/06 at 16:53 ~ permalink