#### Upcoming Schedule

• Wednesday, 6-8:30pm: Help Hours in Olsson 001
• Thursday, 11am-noon: Extra Office Hours in Olsson 236A
• Friday, 18 September: Finish reading Chapter 5
• Monday, 21 September: Chapter 6
• Wednesday, 23 September: Problem Set 3
• Friday, 25 September: Chapter 7
• Monday, 28 September: Chapter 8
• Wednesday, 30 September: Problem Set 4
• Friday, 2 October: Exam 2 out
• Wednesday, 7 October: Exam 2 due

#### Problem Set 2 Comments

The PS2 Comments are posted on the course website.
```(define (find-best f p)
(if (null? (cdr p))
(car p)
(pick-best f (car p)
(find-best f (cdr p)))))

(define (pick-best f a b)
(if (f a b) a b))
```
How can we define find-best-hand using find-bestiest?

#### Mapping Lists

Define a procedure list-map that takes two inputs, a procedure and a list and produces as output a list whose elements are the results of applying the input procedure to each element in the input list.

```

```
What do each of these expressions mean:
```(define (mystery-one p)
(list-map (lambda (x) (if (< x 0) (- x) x))) p))

(define (mystery-two p)
(list-map list-sum p))

(define (mystery-three p)
(list-map
(lambda (q)
(list-map (lambda (n) (odd? n)) q))
p))

```
Could you use list-map to count the number of odd numbers in a list?
```

```
Could you use list-map to produce a list that is the input list with all the odd numbers removed? (e.g., input: (1 2 3 4), output: (2 4)).
```

```