Projects layout plus pen-and-paper proofs

Admin Stuff

HW, Projects, Meetings

Time to talk in class on this

Examples

Cryptarithmetic Send + More = Money etc

  CAN
+ GET
----------
 CASH

  CAN
+ HAS
----------
 CASH

Sudoku, and discuss how it’s done
Crossword w/a dictionary: feasible?
map coloring problem, map coloring + oblasts?
word search w/<=k words?
Marble/peg solitaire 15 golf ball tees puzzle
(n-queens)
Rubix cube (show example solns) Do we know what the most complicated configurations are for a rubix cube??

Meeting time.

HW 5, 8 should be lighter.

(Lighter HW B/C of project)

3. Write the sentence “I am taking this extra time to work on our project!”

The pen-and-paper prover isn’t fully battle-ready.

Class Examples of Pen-and-Paper Proofs.

  (definec len2 (x :tl) :nat
	(if (endp x)
		0
	  (+ 1 (len2 (rest x)))))

  (definec in2 (a :all l :tl) :bool
	(if (endp l)
		nil
	  (or (== a (first l)) (in2 a (rest l)))))

  (definec app2 (x :tl y :tl) :tl
	(if (endp x)
		y
	  (cons (first x) (app2 (rest x) y))))

  (definec rev2 (x :tl) :tl
	(if (endp x)
		x
	  (app2 (rev2 (cdr x)) (list (car x)))))

Is this true?

lisp (implies (endp ls) (implies (tlp ls) (implies (in2 a ls) (in2 a (rev2 ls))))

lisp (implies (consp ls) (implies (implies (tlp (rest ls)) (implies (in2 a (rest ls)) (in2 a (rev2 (rest ls))))) (implies (tlp ls) (implies (in2 a ls) (in2 a (rev2 ls)))))