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Difference between revisions of "Central algebra"

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m (Corrected error: The tensor product of a CSA with a SA is _not_ central, except if the SA is actually a CSA too)
(Category:Associative rings and algebras)
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An algebra with a unit element over a field, the centre of which (see [[Centre of a ring|Centre of a ring]]) coincides with the ground field. For example, the division ring of quaternions is a central algebra over the field of real numbers, but the field of complex numbers is not. An algebra of matrices over a field is a central algebra. The tensor product of a simple algebra and a [[central simple algebra]] is a simple algebra, which is central if and only if the first one is. Every automorphism of a finite-dimensional central simple algebra is inner and its dimension is the square of an integer.
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An algebra with a unit element over a field, the centre of which (see [[Centre of a ring|Centre of a ring]]) coincides with the ground field. For example, the division ring of quaternions is a central algebra over the field of real numbers, but the field of complex numbers is not. The full [[matrix algebra]] over a field is a central algebra. The tensor product of a simple algebra and a [[central simple algebra]] is a simple algebra, which is central if and only if the first one is. Every automorphism of a finite-dimensional central simple algebra is inner and its dimension is the square of an integer.
  
 
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<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  R.S. Peirce,  "Associative algebras" , Springer  (1980)</TD></TR><TR><TD valign="top">[a2]</TD> <TD valign="top">  A.A. Albert,  "Structure of algebras" , Amer. Math. Soc.  (1939)</TD></TR><TR><TD valign="top">[a3]</TD> <TD valign="top">  M. Deuring,  "Algebren" , Springer  (1935)</TD></TR><TR><TD valign="top">[a4]</TD> <TD valign="top">  I.N. Herstein,  "Noncommutative rings" , Math. Assoc. Amer.  (1968)</TD></TR><TR><TD valign="top">[a5]</TD> <TD valign="top">  N. Jacobson,  "Structure of rings" , Amer. Math. Soc.  (1956)</TD></TR></table>
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<table>
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<TR><TD valign="top">[a1]</TD> <TD valign="top">  R.S. Peirce,  "Associative algebras" , Springer  (1980)</TD></TR>
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<TR><TD valign="top">[a2]</TD> <TD valign="top">  A.A. Albert,  "Structure of algebras" , Amer. Math. Soc.  (1939)</TD></TR>
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<TR><TD valign="top">[a3]</TD> <TD valign="top">  M. Deuring,  "Algebren" , Springer  (1935)</TD></TR>
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<TR><TD valign="top">[a4]</TD> <TD valign="top">  I.N. Herstein,  "Noncommutative rings" , Math. Assoc. Amer.  (1968)</TD></TR>
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<TR><TD valign="top">[a5]</TD> <TD valign="top">  N. Jacobson,  "Structure of rings" , Amer. Math. Soc.  (1956)</TD></TR>
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</table>
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[[Category:Associative rings and algebras]]

Revision as of 19:49, 7 November 2014

An algebra with a unit element over a field, the centre of which (see Centre of a ring) coincides with the ground field. For example, the division ring of quaternions is a central algebra over the field of real numbers, but the field of complex numbers is not. The full matrix algebra over a field is a central algebra. The tensor product of a simple algebra and a central simple algebra is a simple algebra, which is central if and only if the first one is. Every automorphism of a finite-dimensional central simple algebra is inner and its dimension is the square of an integer.

References

[1] Yu.A. Drozd, V.V. Kirichenko, "Finite-dimensional algebras" , Kiev (1980) (In Russian)
[2] L.A. Skornyakov, "Elements of general algebra" , Moscow (1983) (In Russian)


Comments

References

[a1] R.S. Peirce, "Associative algebras" , Springer (1980)
[a2] A.A. Albert, "Structure of algebras" , Amer. Math. Soc. (1939)
[a3] M. Deuring, "Algebren" , Springer (1935)
[a4] I.N. Herstein, "Noncommutative rings" , Math. Assoc. Amer. (1968)
[a5] N. Jacobson, "Structure of rings" , Amer. Math. Soc. (1956)
How to Cite This Entry:
Central algebra. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Central_algebra&oldid=34324
This article was adapted from an original article by L.A. Skornyakov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article