General Questions
E-mail
Printing
Teaching
Mathematical Computation
General Questions
Q: How do I get an account on the Math department computer system?
A:
New faculty and graduate students in the Ph.D. program should see Peter Woit in Room 421 soon after they arrive to set up a computer account. Visitors who are here for more than a day or two and would like to use the computer system should also see Peter about this.
Q: How do I get an account on the main university computer system?
A:
All new faculty and students should set up an account on the main university computer system. To do this you need to know your "UNI", which is generally your initials followed by a number. You should be able to get this from Terrance Cope. The university web-site for managing UNI accounts is
here.
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E-mail
Q: Why am I getting so much spam, can't something be done about it?
A:
The math mail server is under continuous attack by an overwhelming amount of spam and virus-laden e-mail. Typically at least 95% of incoming mail is spam or viruses. The server is becoming increasingly heavily loaded trying to deal with this onslaught.
We are using three main systems to deal with the problem:
1. The mail server rejects incoming connections from addresses listed on various "BlockLists" which try and maintain lists of addresses used by spammers including PCs that have been trojanned and are being used to send out spam and viruses. The main problem is such PCs, which often each time they are turned on get a new dynamic address.
2. A virus detector called "ClamAV" scans all mail for viruses and rejects virus-laden mail. This is run by a program called MimeDefang, which also rejects all mail containing certain categories of attachments that are rarely used except by viruses.
3. A Spam detector called "SpamAssassin" analyses all the rest of the incoming e-mail and assigns it a score based on a very complex algorithm using many different rules. Higher scores mean higher probability that the e-mail is spam. The algorithms used incorporate Bayesian learning techniques. One reason for some of the random looking spam you see is that it is an attempt by spammers to defeat or poison this kind of analysis. E-mail with a spam score of 9 or above is automatically deleted and not delivered. I have never seen a legitimate piece of e-mail with score 9 or above. E-mail with scores above a value that you can change yourself by editing the value of "required_score" (or "required_hits", same thing) in the file
.spamassassin/user_prefs
is tagged in the subject line as "SPAM". The default value is 7, you may want to try making this smaller. Smaller values will identify more spam, but will increase the probability of misidentifying legitimate mail.
You can also blacklist and whitelist specific addresses using "blacklist_from" and "whitelist_from" entries in the user_prefs file.
If you want to automatically do something about the mail tagged as "SPAM", you can do so by putting an appropriate ".procmailrc" file in your home directory. If you do
cp /usr/local/etc/procmailrc.deletespam .procmailrc
all such mail will be automatically deleted before you see it.
If you do
cp /usr/local/etc/procmailrc.savespam .procmailrc
all such mail will be saved in a mail folder called "Spam". I've been doing this for a while, and have never seen a legitimate message to me ending up there, using the default cut-off of 7. If you do this, please empty this "Spam" mail folder regularly. If you accumulate a large one, it will sooner or later be deleted without asking you.
Q: How do I read my e-mail on the Math department computer system?
A:
The two simplest mail programs to use are:
Pine: this is a text-based program that does not require a graphics environment, and so can be run from any terminal window on the Linux machines, or any terminal program on another computer. It can be started by typing "pine". For more information about its features and how to use them, see the web-site of the
Pine Information Center.
Webmail (IMP): this is a web-based program that provides access to your e-mail using the department web-server. It can be used from any web-browser on any computer attached to the internet. The program is started by clicking on "Email" in the upper right-hand corner of the department web-site (or
here).
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Printing
Q: What is the name of the printer in (location)?
A:
The default printer for the Linux system is the one in Mathematics 421. If you are using this you do not need to specify a printer name. Other printers in semi-public locations are given names according to the scheme
"RoomNumber"Printer, e.g. the printer in 421 is
421Printer, the one in the fourth-floor graduate student office is
408Printer. One exception is the color printer in the main office, room 509, which is named 509ColorPrinter. Printers in individual offices are given names according to the scheme
"LastName"Printer.
For a complete current list of the department printers, see the
CUPS Printers web-page on the Math department web-server.
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Teaching
Q: What is Webwork?
A:
Webwork is a system for on-line homework assignments developed at the University of Rochester. At the current time we are using it in our Calculus I and Calculus II classe. These classes have a teaching assistant assigned to them who is responsible for Webwork issues, and who should be able to provide help with any problems you have in using the system.
Q: What is Courseworks?
A:
Courseworks is the universities course-management system. It.....
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Mathematical Computation
Q: What computers are available for long computations?
A:
Please do not use the main server (cpw.math.columbia.edu=math.columbia.edu) for time-consuming computations. These can be done on any of the local Linux workstations or on two machines specifically dedicated to this purpose:
- video.math.columbia.edu This machine is has two hyperthreaded 3 Ghz P4 processors and 4GB of RAM
- fdr.math.columbia.edu This machine is physically identical to cpw. It has four 700 Mhz PIII processors and 4 GB of RAM.
For security reasons, you can only log into these machines from cpw, and need to first ask Peter Woit to put your account name on a list of those allowed to access these machines.
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