Posts in 2011

 

Pretend Invitations

Choosing between people you want to invite to a function and people you have to invite is sometimes difficult. Say Alice wants to invite Tom, Dick, and Harry to a party, but she'd actually prefer if Dick didn't show up. Here's how Alice can send invitations by email from an email-capable Unix system to achieve the desired result, while covering her scheming with plausible deniability.

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Advice from Successful Greek IT Startups

Members of the Hellenic Association of Mobile Application Companies and the Hellenic Semiconductor Industry Association, assorted biotechnology companies, and representatives from Greek and US-based venture capital funds gathered on Friday December 17, 2011 in a meeting to exchange advice, tips, and war stories on venturing abroad. It was one of the most inspiring meetings I've attended for some time. These are my notes from the meeting.

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Apps are the New Users

Some facilities provided by mature multi-user operating systems appear arcane today. Administrators of computers running Mac OS X or Linux can see users logged-in from remote terminals, they can specify limits on the disk space one can use, and they can run accounting statistics to see how much CPU time or disk I/O a user has consumed over a month. These operating systems also offer facilities to group users together, to specify various protection levels for each user's files, and to prescribe which commands a user can run.

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Using the HP 4470c Scanner Under Windows 7

Neither Hewlett Packard nor Microsoft Windows 7 offer native support for my HP 4470c scanner. Throwing a working scanner away to buy a new one only because some software was missing seemed like a waste, so I looked for an alternative solution. This is how I made it work using SANE, an open source framework for scanners.

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Lessons from Space

By Diomidis Spinellis and Henry Spencer

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Faking it

This column is about a tool we no longer have: the continuous rise of the CPU clock frequency. We were enjoying this trend for decades, but in the past few years, progress stalled. CPUs are no longer getting faster because their makers can’t handle the heat of faster-switching transistors. Furthermore, increasing the CPU’s sophistication to execute our instructions more cleverly has hit the law of diminishing returns. Consequently, CPU manufacturers now package the constantly increasing number of transistors they can fit onto a chip into multiple cores—processing elements—and then ask us developers to put the cores to good use.

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Impact Factor of Computer Science Journals 2010

The Thomson Reuters Web of Knowledge has published the 2010 Journal Citation Reports. Following similar studies I performed in 2007, 2008, 2009, and 2010, here is my analysis of the current status and trends for the impact factor of computer science journals.

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How I Dealt with Student Plagiarism

Panos Ipeirotis, a colleague at the NYU Stern School of Business, received considerable media attention when, in a blog post he subsequently removed, he discussed how his aggressive use of plagiarism detection software on student assignments poisoned the classroom atmosphere and tanked his teaching evaluations. As detailed in a story posted on the Chronicle of Higher Education blog, Mr. Ipeirotis proposes instead that professors should design assignments that cannot be plagiarized. Along these lines here are two methods I've used in the past.

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Agility Drivers

When the facts change, I change my mind. What do you do, sir?

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Ten Lessons I Learned from Fixing my Laptop's Motherboard

A month ago I managed to break my laptop, by reversing the polarity of a universal power supply. The repair shop diagnosed the problem as a failed motherboard, and asked for €659 to replace it. I found the price preposterous and the notion of throwing away a motherboard for a single failed component ecologically unsound. Here is how I fixed the laptop on my own, and what I learned in the process.

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Code Verification Scripts

Which of my classes contain instance variables? Which classes call the method userGet, but don't call the method userRegister? These and similar questions often come up when you want to verify that your code is free from some errors. For example, instance variable can be a problem in servlet classes. Or you may have found a bug related to the userGet and userRegister methods, and you want to look for other places where this occurs. Your IDE is unlikely to answer such questions, and this is where a few lines in the Unix shell can save you hours of frustration.

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Choosing and Using Open Source Components

The developers of the SQLite open source database engine estimate that it’s deployed in roughly half a billion systems around the world (users include Airbus, Google, and Skype). Think of the hundreds of thousands of open source components, just one click away from you. If you know how to choose and use them effectively , your project can benefit mightily.

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elytS edoC

Sure, you can write English right to left. You can also write software code to look like a disc or even a train (see www.ioccc.org/1988/westley.c and 1986/marshall.c). However, you can’t then complain when you have to fight with your magazine’s editor or production staff about accepting your column’s title for publication, or if your colleagues refuse to touch your code with a 10-foot pole. Writing code in a readable and consistent style is difficult, uninteresting, tedious, underappreciated, and, extremely important.

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Sophisticated Targeted Link Spam

What appeared to be an intelligent comment in one of my blog postings turned out to be targeted link spam. This is a worrying trend, because, although we can defend ourselves against mass attacks, we're very vulnerable to targeted strikes.

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