资料来源 : pyDict

代数学

资料来源 : Webster's Revised Unabridged Dictionary (1913)

Algebra \Al"ge*bra\, n. [LL. algebra, fr. Ar. al-jebr reduction
   of parts to a whole, or fractions to whole numbers, fr.
   jabara to bind together, consolidate; al-jebr
   w'almuq[=a]balah reduction and comparison (by equations): cf.
   F. alg[`e]bre, It. & Sp. algebra.]
   1. (Math.) That branch of mathematics which treats of the
      relations and properties of quantity by means of letters
      and other symbols. It is applicable to those relations
      that are true of every kind of magnitude.

   2. A treatise on this science.

Mathematics \Math`e*mat"ics\, n. [F. math['e]matiques, pl., L.
   mathematica, sing., Gr. ? (sc. ?) science. See {Mathematic},
   and {-ics}.]
   That science, or class of sciences, which treats of the exact
   relations existing between quantities or magnitudes, and of
   the methods by which, in accordance with these relations,
   quantities sought are deducible from other quantities known
   or supposed; the science of spatial and quantitative
   relations.

   Note: Mathematics embraces three departments, namely: 1.
         {Arithmetic}. 2. {Geometry}, including {Trigonometry}
         and {Conic Sections}. 3. {Analysis}, in which letters
         are used, including {Algebra}, {Analytical Geometry},
         and {Calculus}. Each of these divisions is divided into
         pure or abstract, which considers magnitude or quantity
         abstractly, without relation to matter; and mixed or
         applied, which treats of magnitude as subsisting in
         material bodies, and is consequently interwoven with
         physical considerations.

资料来源 : WordNet®

algebra
     n : the mathematics of generalized arithmetical operations

资料来源 : Free On-Line Dictionary of Computing

algebra
     
         1. A loose term for an {algebraic
        structure}.
     
        2. A {vector space} that is also a {ring}, where the vector
        space and the ring share the same addition operation and are
        related in certain other ways.
     
        An example algebra is the set of 2x2 {matrices} with {real
        numbers} as entries, with the usual operations of addition and
        matrix multiplication, and the usual {scalar} multiplication.
        Another example is the set of all {polynomials} with real
        coefficients, with the usual operations.
     
        In more detail, we have:
     
        (1) an underlying {set},
     
        (2) a {field} of {scalars},
     
        (3) an operation of scalar multiplication, whose input is a
        scalar and a member of the underlying set and whose output is
        a member of the underlying set, just as in a {vector space},
     
        (4) an operation of addition of members of the underlying set,
        whose input is an {ordered pair} of such members and whose
        output is one such member, just as in a vector space or a
        ring,
     
        (5) an operation of multiplication of members of the
        underlying set, whose input is an ordered pair of such members
        and whose output is one such member, just as in a ring.
     
        This whole thing constitutes an `algebra' iff:
     
        (1) it is a vector space if you discard item (5) and
     
        (2) it is a ring if you discard (2) and (3) and
     
        (3) for any scalar r and any two members A, B of the
        underlying set we have r(AB) = (rA)B = A(rB).  In other words
        it doesn't matter whether you multiply members of the algebra
        first and then multiply by the scalar, or multiply one of them
        by the scalar first and then multiply the two members of the
        algebra.  Note that the A comes before the B because the
        multiplication is in some cases not commutative, e.g. the
        matrix example.
     
        Another example (an example of a {Banach algebra}) is the set
        of all {bounded} {linear operators} on a {Hilbert space}, with
        the usual {norm}.  The multiplication is the operation of
        {composition} of operators, and the addition and scalar
        multiplication are just what you would expect.
     
        Two other examples are {tensor algebras} and {Clifford
        algebras}.
     
        [I. N. Herstein, "Topics_in_Algebra"].
     
        (1999-07-14)