lecture3

lecture3 - Click to edit Master subtitle style Class 3:...

This preview shows pages 1–10. Sign up to view the full content.

Click to edit Master subtitle style 2/19/10 Class 3: Rules of Evaluati on David Evans cs1120 Fall 2009

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2/19/10 Menu Questions from Notes Computing photomosaics, non-recursive languages, hardest language elements to learn Scheme’s Rules of Evaluation (break: Survey Responses) 22
2/19/10 If it takes 60 seconds to compute a photomosaic for Problem Set 1 today on a typical PC, estimate how long it will take cs1120 students in 2012 to compute the same photomosaic? How long will it take in 2015? > (/ (* (- 2012 2009) 12) 18) 2 > (/ 60 (* 2 2)) 15 > (/ (* (- 2015 2009) 12) 18) 4 > (/ 60 (* 2 2 2 2)) 15/4 > (exact->inexact (/ 60 (* 2 2 2 2))) 3.75 Difference in years * 12 = number of months Number of months / 18 = number of doublings according to Moore’s Law 60 seconds today, 2 doublings by 2012 15 seconds in 2012 60 seconds today, 4 doublings by 2015 3.75 seconds in 2015 Reality check: Moore’s “law” is just an “observation”. 33

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2/19/10 Are there any non-recursive natural languages? What would happen to a society that spoke one? Not for humans at least. They would run out of original things to say. Chimps and Dolphins are able to learn non-recursive “languages”, but only humans have learned recursive languages . 44
2/19/10 Running out of Ideas “Its all been said before.” Eventually true for a non-recursive language. Never true for a recursive language. There is always something original left to say! 55

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2/19/10 Language Elements When learning a foreign language, which elements are Primitives: lots of them, and hard to learn real meaning Means of Combination Complex, but, all natural languages have similar ones [Chomsky] SOV (45% of all languages) Sentence ::= Subject Object Verb (Korean) SVO (42%) Sentence ::= Subject Verb Object (English) VSO (9%) Sentence ::= Verb Subject Object (Welsh) “Lladdodd y ddraig y dyn.” (Killed the dragon the man.) OSV (<1%): Tobati (New Guinea) Scheme: Means of Abstraction: few of these, but tricky to learn Expression ::= ( Verb Object ) defin e 66
Pages in Revised5 Report on the Algorithmic Language Scheme Primitives Means of Combinati on Means of Abstractio n 48 pages total (includes formal specification and examples)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Pages in Revised5 Report on the Algorithmic Language Scheme Primitives Standard Procedures Primitive expressions Identifiers, numerals 18 2 1 Means of Combinati on Expressions Program structure 2 2 Means of Abstractio n Definition s ½ 48 pages total (includes formal
Pages in Revised5 Report on the Algorithmic Language Scheme Pages in C++ Language

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

lecture3 - Click to edit Master subtitle style Class 3:...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online