A Clifford algebra is an associative algebra associated with an -dimensional
vector space over a field and a quadratic form on . In the sign convention used here, it is generated by subject to the multiplication rule
(1)
for every ,
where
is the multiplicative identity .
More precisely, the Clifford algebra is the quotient of the tensor algebra by the two-sided ideal generated by for . When the field characteristic
of
is not 2, the defining rule also gives
(2)
where
is the symmetric bilinear form associated
with .
For
with
an Euclidean space and , an orthonormal
basis
satisfies
for .
The products
with ,
together with the empty product , form a vector basis of the
Clifford algebra. Its dimension is therefore .
Clifford algebras are generally not commutative . When
is identically zero, the Clifford algebra is the exterior
algebra of .
Clifford algebras are used to define spinors .
In the Wolfram Language , CliffordAlgebra represents Clifford algebras with generators whose squares are , , or 0. NonCommutativeExpand
puts expressions in these algebras into canonical form .
See also Algebra ,
Dirac Matrices ,
Exterior Algebra ,
Geometric
Algebra ,
Hypercomplex Number ,
Quadratic
Form ,
Quaternion ,
Spinor ,
Spinor Field ,
Tensor
Algebra ,
Vector Space
Portions of this entry contributed by Todd
Rowland
Explore with Wolfram|Alpha
References Abłamowicz, R. "Hecke Algebra, SVD, and Other Computational Examples with CLIFFORD." 14 Oct 1999. https://arxiv.org/abs/math/9910069 . Ablamowicz,
R.; Lounesto, P.; and Parra, J. M. Clifford
Algebras with Numeric and Symbolic Computations. Boston, MA: Birkhäuser,
1996. Huang, J.-S. "The Clifford Algebra." §6.2 in Lectures
on Representation Theory. Singapore: World Scientific, pp. 63-65, 1999. Iyanaga,
S. and Kawada, Y. (Eds.). "Clifford Algebras." §64 in Encyclopedic
Dictionary of Mathematics. Cambridge, MA: MIT Press, pp. 220-222, 1980. Lawson,
H. B., Jr. and Michelsohn, M.-L. Spin
Geometry. Princeton, NJ: Princeton University Press, 1989. Lounesto,
P. Clifford
Algebras and Spinors, 2nd ed. Cambridge, England: Cambridge University Press,
2001. Lounesto, P. "Counterexamples to Theorems Published and Proved
in Recent Literature on Clifford Algebras, Spinors, Spin Groups, and the Exterior
Algebra." http://www.helsinki.fi/~lounesto/counterexamples.htm . Penrose,
R. §11.5 in Road
to Reality: A Complete Guide to the Laws of the Universe. New York: Knopf,
2004. Referenced on Wolfram|Alpha Clifford Algebra
Cite this as:
Weisstein, Eric W. , with contributions by Todd Rowland . "Clifford Algebra." From MathWorld --A
Wolfram Resource. https://mathworld.wolfram.com/CliffordAlgebra.html
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