Solution
= Solution
{c}
A <continuous map> $f:X\to Y$ is one for which $f^{-1}(U)$ is open in $X$ whenever $U$ is open in $Y$. This defines continuity using the two <topologies>, without a metric or a coordinate description.
= Solution
{c}
A <continuous map> $f:X\to Y$ is one for which $f^{-1}(U)$ is open in $X$ whenever $U$ is open in $Y$. This defines continuity using the two <topologies>, without a metric or a coordinate description.