May 13

Questions?

1-on-1 project meetings ... please pick a spot. We're doing these on Monday & Tuesday instead of our regular class.

... start recording.

a pinch of complexity theory

Continue our meander through some ideas from complexity theory using my notes from last class and these discussion points :

• CS fields of study
• hanoi.py - what complexity class is this in? Does this fit into one of "easy" (P) or "hard" (NP) categories?
• last part of Zelle's chap 13 slides (from Intro CS textbook)
• What is a "regular expression"? A "finite state machine"? How are those connected?
  • practice at regexcrosswords.com
• What is a turing machine? Why is it so famous?
  • Here is my virtual turing machine (in python).
• What is the halting problem? Does that fit into P or NP?
• What is Gödel's incompleteness theorem? Why is it related?
• Can a computer tell if a file is a well-formed python program?
  • (See for example its grammar.)
  • It can be defined with a context free grammar .
  • ... which it turns out can be done with a kind of computer called a "pushdown automata", type-2
  • ... smarter than a finite state machine (type-3) not as smart as a turing machine (type-0)
• How do the (sorting, graph, search) algorithms we've been discussing fit into this framework?
• Can a computer be a person? What are your reasons for arguing "yes" or "no"?
  • And are we "meat machines", software minds running in hardware brains?
  • See for example Scott Aaron's discussion .

(Are we having fun yet?)