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Gene Callahan
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Gene Callahan

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Introduction to Algorithms, Lecture Three
Here .
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Gene Callahan

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Will-ful Ignorance
Will Wilkinson thinks he's got the religious dead to rights : "It’s happening in all wealthy, liberal-democratic countries. The needs served by religious belief and participation seem to weaken as people become more prosperous and oriented toward individual...
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Gene Callahan

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Any Maor Dude with Half a Pile of Uranium
Relevant to our recent discussion of the continuum: "The rate of decay of a radioactive substance -- in the amount of radiation it emits -- is at every moment proportional to its mass m : dm/dt = -am . The solution of this differential equation is m = m 0 e...
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Gene Callahan

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Zeno was not worrying about specifications or formal systems
Reader Alex Small writes : "the fact that we can specify a process via an infinite list of statements does not mean that it is impossible for such a process to happen. There is an implicit assumption that the only physically feasible processes are those wit...
Reader Alex Small writes: "the fact that we can specify a process via an infinite list of statements does not mean that it is impossible for such a process to happen. There is an implicit assumption that the only physically f...
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Gene Callahan

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Gotta have a right for this, a right for that
At a faculty meeting recently, I was told that it is a "human right" of students to have a syllabus that tells them what is expected of them in a course.
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Gene Callahan

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Micro-Bias
Microwave, that is. I assume that there is an ideal cooking time for any particular dish one might put in the microwave. Furthermore, there is no reason to suppose that these ideal cooking times tend to fall particularly often on multiples of 60 seconds. Bu...
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Gene Callahan

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Professors, Don't Let Your Students Grow Up to Be Proprietary Software Users
I am currently cutting over all of my course management to rely on open-source, text-reliant software and files. I have been through several course management tool cut-overs at several schools, plus experiencing the general difficulty of bringing one's accu...
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Gene Callahan

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"Don't Shoot Him!"
The New York Times has on its front page for Sunday (we get the Sunday Times on Saturday in NYC): '"Don't Shoot Him!" Wife's Plea to Charlotte Police' This is incendiary. More relevant and less inflammatory would have been '"Drop the Gun!" Cop's Plea to Cha...
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Gene Callahan

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Any Maor Dude with Half a Pile of Uranium
"The rate of decay of a radioactive substance -- in the amount of radiation it emits -- is at every moment proportional to its mass m : dm/dt = -am . The solution of this differential equation is m = m 0 e -at , where m 0 is the initial mass of the substanc...
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Gene Callahan

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Does Accounting for Time Somehow Resolve Zeno's Paradoxes?
A commenter asks, "Isn't Zeno's mistake thinking that an infinite number of steps cannot be completed in a finite time?" Upon receiving this question, I realize that I have been making a mistake: I have been presenting Zeno's paradox as it usually, in my ex...
A commenter asks, "Isn't Zeno's mistake thinking that an infinite number of steps cannot be completed in a finite time?" Upon receiving this question, I realize that I have been making a mistake: I have been presenting Zeno's...
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Gene Callahan

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Textbook speak
I just ran across the following problem in a business math textbook: "Joe, at age 35, decides to invest in a retirement account. He will put aide $2000 per year for the next 30 years. How much will he have at age 65 if his rate of return is assumed to be 10...
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Gene Callahan

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My review of The Cambridge Economic History of Modern Britain, Volume I
is now online here .
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