Definition:Codimension
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Definition
For an arbitrary submanifold $Z$ of a manifold $X$, the codimension of $Z$ in $X$ is the dimension of $X$ minus the dimension of $Z$.
For an arbitrary submanifold $Z$ of a manifold $X$, the codimension of $Z$ in $X$ is the dimension of $X$ minus the dimension of $Z$.