Question 21
be $\mathcal{P}$ the set of the points of the plane and $f: \mathcal{P} \rightarrow \mathcal{P}$ An application that meets the following three conditions:
a) $f$ It is bijective.
b) for each line $r$ from the plane, $f(r)$ It's a straight.
c) for each line $r$, the straight $f(r)$ Is it parallel or coincident with $r$. What possible transformations can be $f$?
a) $f$ It is bijective.
b) for each line $r$ from the plane, $f(r)$ It's a straight.
c) for each line $r$, the straight $f(r)$ Is it parallel or coincident with $r$. What possible transformations can be $f$?