1 ;; The first three lines of this file were inserted by DrScheme. They record metadata
2 ;; about the language level of this file in a form that our tools can easily process.
3 #reader(lib "htdp-advanced-reader.ss" "lang")((modname |30.2|) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
4 A node is a symbol.
5 
6 A pair is a list
7 (cons n1 (cons n2)), ie, (list n1 n2)
8 where n1 and n2 are symbols representing nodes.
9 
10 A simple-graph is a (listof pairs).
11 
12 route-exists? : node node sg (listof nodes) -> boolean