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Category vs Index - What's the difference?

category | index |

In mathematics terms the difference between category and index

is that category is a collection of objects, together with a transitively closed collection of composable arrows between them, such that every object has an identity arrow, and such that arrow composition is associative while index is a raised suffix indicating a power.

As nouns the difference between category and index

is that category is a group, often named or numbered, to which items are assigned based on similarity or defined criteria while index is an alphabetical listing of items and their location.

As a verb index is

to arrange an index for something, especially a long text.

As a proper noun Index is

a town in Washington.

category

Noun

(categories)
  • A group, often named or numbered, to which items are assigned based on similarity or defined criteria.
  • *
  • The traditional way of describing the similarities and differences between constituents is to say that they belong to categories'' of various types. Thus, words like ''boy'', ''girl'', ''man'', ''woman'', etc. are traditionally said to belong to the category''' of Nouns, whereas words like ''a'', ''the'', ''this'', and ''that'' are traditionally said to belong to the ' category of Determiners.
    This steep and dangerous climb belongs to the most difficult category .
    I wouldn't put this book in the same category as the author's first novel.
  • (mathematics) A collection of objects, together with a transitively closed collection of composable arrows between them, such that every object has an identity arrow, and such that arrow composition is associative.
  • One well-known category has sets as objects and functions as arrows.
    Just as a monoid consists of an underlying set with a binary operation "on top of it" which is closed, associative and with an identity, a category consists of an underlying digraph with an arrow composition operation "on top of it" which is transitively closed, associative, and with an identity at each object. In fact, a category's composition operation, when restricted to a single one of its objects, turns that object's set of arrows (which would all be loops) into a monoid.

    Synonyms

    * (group to which items are assigned) class, family, genus, group, kingdom, order, phylum, race, tribe, type * See also

    Derived terms

    * category mistake * category theory * conceptual category * perceptual category * subcategory * supercategory

    index

    English

    (wikipedia index)

    Noun

    (en-noun)
  • An alphabetical listing of items and their location.
  • The index of a book lists words or expressions and the pages of the book upon which they are to be found.
  • The index finger; the forefinger.
  • A movable finger on a gauge, scale, etc.
  • (printing) A symbol resembling a pointing hand, used to direct particular attention to a note or paragraph.
  • That which points out; that which shows, indicates, manifests, or discloses.
  • * Arbuthnot
  • Tastes are the indexes of the different qualities of plants.
  • A sign; an indication; a token.
  • * Robert Louis Stevenson
  • His son's empty guffaws struck him with pain as the indices of a weak mind.
  • (linguistics) A type of noun where the meaning of the form changes with respect to the context. E.g., 'Today's newspaper' is an indexical form since its referent will differ depending on the context. See also icon and symbol.
  • (economics) A single number calculated from an array of prices or of quantities.
  • (science) A number representing a property or ratio, a coefficient.
  • (mathematics) A raised suffix indicating a power.
  • (programming, computing) An integer or other key indicating the location of data e.g. within an array, vector, database table, associative array, or hash table.
  • (computing, databases) A data structure that improves the performance of operations on a table.
  • (obsolete) A prologue indicating what follows.
  • (Shakespeare)

    Synonyms

    * (index finger) arrow-finger, demonstrator, forefinger, index finger, insignitor, lickpot, pointling, showing finger, teacher * See also

    Derived terms

    * index locorum * index nominum * index rerum * index term * index verborum * indexic * indexical * indexless * price index * refractive index

    References

    *

    See also

    * (alphabetical listing) table of contents

    Verb

    (es)
  • To arrange an index for something, especially a long text.
  • To inventory, to take stock.
  • Derived terms

    * indexer