The phrase "are indexed by a" is correct and usable in written English.
It can be used in contexts where you are describing how items, data, or elements are organized or categorized according to a specific criterion or identifier.
Example: "The documents are indexed by a unique identifier to facilitate easy retrieval."
Alternatives: "are categorized by a" or "are organized by a".
In routinely testing the values of the mean or variance of a distribution, $H'$ is often a composite hypothesis whose components are indexed by a parameter $\theta$ (e.g., $H: \theta = \theta_0$ is tested against $H': \theta \ne \theta_0$).
Such evidential corpora are indexed by a significance level at which the claims in the corpus are valid.
As in [35], the bifurcating periodic solutions (y t, mu)) of system (3.1) are indexed by a small parameter ε.
(i) Even though the aforementioned expressions are indexed by a resource element, in LTE, a resource element represents 1 sub-carrier (15 KHz) over 1 OFDM symbol (approximately 70 microseconds).
The angular brackets, denote an average over a unit sphere The variables in the displacement gradient tensor, x and are indexed by a Cartesian coordinate system attached to the particle.
A petroleum reservoir grid is a finite, regular grid in one to three dimensions, and its gridding cells are indexed by a positive integer s, where s takes on values in (S = { 1,2, ldots,n}).
Institutional and noninstitutional maps are indexed by an off-line procedure through their metadata, managed by a metadata catalogue service.
By all accounts, referential changes and spatial inference triggered by conjunctions would both be indexed by a P600, reflecting updating of a mental model (Brouwer et al., 2012; Donchin & Coles, 1988).
Whilst we believe that future studies are needed to definitively establish whether above-chance levels of inferential performance are possible in the absence of relational hierarchy knowledge where this is indexed by a continuous hierarchy recall measure we do acknowledge that this may well be the case.
Time slots are indexed by, with as an index set.
Moreover, we assume that channels in S ̂ a are indexed by 1,2,…,k m a x.
