$($b$)$ Space representation $($mapping$)$ is one of the important issues to be addressed in robot

navigation, for the purpose of path planning. The following two figures show maps that

are constructed for the same indoor environment.

Figure $2\mathrm{.}1$ Figure $2\mathrm{.}2$

$($i$)$ What are the names for each of these two maps?

$($ii$)$ Describe briefly the basic idea of each of these two maps.