# Note learning prerequisites

Hi
I think we should have an option to link notes with others in a way that a note doesn’t show up until you learn the notes linked to it
This is useful in math when learning something new in shared decks
For example:
Note a:
$$\overrightarrow{a}\cdot\overrightarrow{b}=\vert\overrightarrow{a}\vert\cdot\vert\overrightarrow{b}\vert\cdot\cos\theta$$
Note b:
$$\cos\theta=\frac{\overrightarrow{a}\cdot\overrightarrow{b}}{\vert\overrightarrow{a}\vert\cdot\vert\overrightarrow{b}\vert}$$

Note b in this case wouldn’t show up until you learn note a because you get b from a.