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# Whitehead group

Whitehead group in mathematics may mean:

A group W with Ext(W, Z)=0; see Whitehead problem

For a ring, the Whitehead group Wh(A) of a ring A, equal to K_1(A)

For a group, the Whitehead group Wh(G) of a group G, equal to K1(Z[G])/{±G}. Note that this is a quotient of the Whitehead group of the group ring.

The Whitehead group Wh(A) of a simplicial complex or PL-manifold A, equal to Wh(π1(A)); see Whitehead torsion.

All named after J. H. C. Whitehead.

Undergraduate Texts in Mathematics

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