Class 2: Language
Slides
[PPTX] [PDF (6 per page for printing)]
Assignments Due
- Now (beginning of class): Course Pledge
- Sunday, 28 August (5:59pm): Submit Problem Set 0
Reading
- Now: should have finished Chapters 1 and 2 of the course book
- Monday: Chapter 3 of course book
- By Friday: Chapter 4 of course book, Chapters 1-3 of James Gleick’s The Information
Upcoming Help Schedule
- Sunday, 28 August (3-5pm): Assistant Coaches’ Help Hours (Joeseph Featherston, Kristina Shichanin in Thorton Stacks) (If you haven’t already successfully submitted PS0, you should definitely take advantage of this to finish PS0!)
- My office hours (and location) will be posted on the course site soon. If you haven’t already, submit http://www.whenisgood.net/cs1120 before 5pm today.
Notes and Questions
Repeat question from Class 1: What other things have changed as much as (or more that!) computing power in your lifetime? (Post your guesses/answers as comments on the course blog.)
What is a language?
Languages are made of:
- Primitives (almost* all languages have these) – the simplest surface forms with meaning (* surprisingly it is possible to make a powerful language without any primitives. We will see one before the end of this class!)
- Means of Combination (all languages have these) – rules of production (ways to make new surface forms from ones you already have)
- Means of Abstraction (all powerful languages have these) – ways to use simple surface forms to represent complicated ones
Backus-Naur Form (BNF): A way of describing the surface forms in a language using replacement rules in the form:
non-terminal ::= replacement
The rule means whenever you have what is on the left side of the ::=, you can replace it with what is on the right side.
What strings can the following BNF grammar produce?
Sentence ::= Food Comparator Food
Food ::= Bodo’s Bagels
Food ::= Einstein’s Bagels
Comparator ::= are better than
Comparator ::= are worse than
What strings can the following BNF grammar produce?
Sentence ::= I like FoodList
FoodList ::= Food
FoodList ::= Food and FoodList
Food ::= Bodo’s Bagels
Food ::= Einstein’s Bagels
When learning a foreign language, which of primitives, means of combination, or means of abstraction is hardest to learn?
Are there any non-recursive natural languages?
What would happen to a society that spoke one?
What is the difference between a compiler and an interpreter?
Steve Jobs, Interviewed in Playboy Magazine, February 1, 1985 (no pictures, other than a fully clothed one of Steve, and just a little bit of bad language) (Note: 3 months later, in May 1985, Jobs was kicked-out of Apple. If you read the whole interview, especially the part about Edwin Land, keep this in mind.)
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When/Where should I expect my partner allocation for PS 01? I submitted my PS 0 yesterday.
The partner assignments for PS1 will be posted before class Monday. If you are ready to start PS1 before then (that is, you’ve finished PS0 and reading Chapters 1-3), contact me and I’ll assign you a partner earlier.