L12_A
3.4 Path-connected Sets
(1)definition
(2)example of a ball
L12_B
3.4 Path-connected Sets(cont.)
(1)example of a continuous map
L12_C
3.4 Path-connected Sets(cont.)
(1)example of a continuous map
3.5 Connected Sets
(1) Question 1:distribution of a subset
(2) Definition & examples
L12_D
In R, a subset A is connected if and only
if it is an interval.
(1)Thm:relation of connected and interval