In mathematics, specifically linear algebra and geometry, relative dimension is the dual notion to codimension.
In linear algebra, given a quotient map, the difference dim V − dim Q is the relative dimension; this equals the dimension of the kernel.
In fiber bundles, the relative dimension of the map is the dimension of the fiber.
More abstractly, the codimension of a map is the dimension of the cokernel, while the relative dimension of a map is the dimension of the kernel.
These are dual in that the inclusion of a subspace of codimension k dualizes to yield a quotient map of relative dimension k, and conversely.
The additivity of codimension under intersection corresponds to the additivity of relative dimension in a fiber product.
Just as codimension is mostly used for injective maps, relative dimension is mostly used for surjective maps.
Famous quotes containing the words relative and/or dimension:
“And since the average lifetime—the relative longevity—is far greater for memories of poetic sensations than for those of heartbreaks, since the very long time that the grief I felt then because of Gilbert, it has been outlived by the pleasure I feel, whenever I wish to read, as in a sort of sundial, the minutes between twelve fifteen and one o’clock, in the month of May, upon remembering myself chatting ... with Madame Swann under the reflection of a cradle of wisteria.”
—Marcel Proust (1871–1922)
“Le Corbusier was the sort of relentlessly rational intellectual that only France loves wholeheartedly, the logician who flies higher and higher in ever-decreasing circles until, with one last, utterly inevitable induction, he disappears up his own fundamental aperture and emerges in the fourth dimension as a needle-thin umber bird.”
—Tom Wolfe (b. 1931)