CS 201 - Spring 2025. 4/14/2025.


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Welcome to CS 201!

Video of the Day

Noam Chomsky
In it, Noam Chomsky argues that recursion –– which is one of the central concepts of our CS201 class –– is what makes human language unique. We can continuously embed phrases sequentially or centrally in ABn format or An x Bn format in order to make sentences. For example,

The bank the man the monkey touched robbed was good. (An x Bn)
The man thought that the monkey thought that the bank would be hard to rob. (ABn)

These utilize recursion because you have to keep parsing the sentences in a parse tree until you hit a 'base case.' This is similar to Racket recursion.

I hereby solicit suggestions for the video of the day. Please email me your ideas with explanations. Selected entries will win 5 homework points. If your video is played at the beginning of class, you must also briefly explain something about the video and something about yourself - in person.

Logical Problem of the day

regex tshirt regex cheat sheet tshirt Linux cheat sheet tshirt

Using grep and the file linux.words in the lectures directory, what regular expression would find all words that contain exactly two x's? (There are 66 such words.)

https://pollev.com/slade You may also download the app to your phone. Use the "slade" poll id.

Canvas Quiz of the Day (need daily password)

Most days, there will be a simple canvas quiz related to the lecture. You need a password to activate the quiz, which I will provide in class. These quizzes will count toward your class participation grade. The quiz is available only during class.

Click for today's quiz.

Lecture 33: Strings and Languages .

  • I have office hours Wednesdays from 4-6 pm, on zoom, id 459 434 2854.

  • I am available for lunch on Mondays at 1 pm in Morse.

  • ULA office hours are found at https://csofficehours.org/CS201/schedule. Sign up via the queue.

  • Homework assignments: [Assignments]. hw7 is now available.

    Midterm 2 Statistics

    Minimum:     24.0
    Maximum:     59.5
    Mean:        50.89
    Median:      53.0
    Standard Deviation: 7.75
    
    The gradescope regrade request window closes at the end of today.

    Remember, if your final exam grade is higher than your lower midterm grade, it will replace that grade. It does not work the other way around though. That would motivate some students to bail on the final exam.

    AI in the News

  • Access to the Atlantic
  • Access to Economist (Economist.com)
  • Access to Financial Times
  • Access to Wall Street Journal from Yale.
  • Q and AI Bloomberg.
  • Access to Bloomberg.com from Yale.

    Announcements

  • If you have an upcoming performance or athletic event, I am happy to promote it during class. Just send me a note.

  • Information Society Project Yale Law School. Weekly Events

  • That Whole "Yale Thing" Video compilation of references to Yale in movies. Friday April 25, 7pm, HQ L02. (list of movies)

    Lecture: Strings and Languages.

    Strings.html (jupyter) regular languages + DFAs.

    review hw7.

    Getting to know UNIX

    UNIX Introduction Principle 5.
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