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COMPUTATIONAL PROBLEMS IN ABSTRACT ALGEBRA.

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An algorithm related to the restricted Burnside<br />

group of prime exponent<br />

E. KRAUSE and K. WESTON<br />

Introduction. Denote the freest Lie ring of characteristic c on n generators<br />

satisfying the mth Engel condition by L(c, n, m).<br />

It is a long-standing conjecture, probably introduced by Sanov, that the<br />

Restricted Burnside Problem for prime exponentp is equivalent to the problem<br />

of nilpotency for L(p, iz, p- 1). In this report we discuss a general algorithm<br />

for Lie rings which analogously to the collection process yields<br />

L(p, IZ, m) (mop) as the latter yields R(p, n). This algorithm is not only<br />

more practical but can be readily used with a computer. For instance we<br />

applied the algorithm aided by a Univac 1107 computer for p = 5, n = 2,<br />

m = 4, and found L(5, 2,4) [l].<br />

An associated matrix algebra of a Lie algebra. Suppose L is a Lie algebra<br />

over a field F spanned by elements /? = {ml, . . . , mk} and Mkxl is the<br />

F-space of kX 1 column matrices over F. Define the coordinate mapping<br />

fp: L - Mk+r by fs(m) = column of coordinates of m EL with respect to<br />

some linear combination of ,!? (i.e. if /3 is not a basis, fs(m) requires a choice<br />

between all of the linear combinations of ,8. In this case any fixed choice is<br />

sufficient for m). If Tis a linear operator of L let M,(T) designate the matrix<br />

whose ith column is fO(T(mi)). Also denote the inner derivation of I E L by<br />

g(Q Then the associated F-algebra Ag of L consists of elements from Mkxl<br />

under ordinary matrix addition and multiplication is defined by<br />

Cl@C, = q9Mf~YC2>>X Cl, Cl, c2E4 (1)<br />

(X denotes matrix multiplication).<br />

The following theorems are easily verified.<br />

THEOREM 1. & is an isomorphism between L and AB if and only if/3 is a<br />

basis.<br />

THEOREM 2. If L(p,n,m)/Lk(p,n,m) is spanned by B = {ml, . . .,m,)<br />

moduIo Lk (p,n,m) then A, is a Lie algebra over GF(p) on n generators satisfying<br />

tlze m-th Engel condition if and only if<br />

A, 2 L(p, n, m>/Lk(p, n, m>.<br />

The associated algebra of a finitely generated Lie algebra. If L is a Lie<br />

algebra with generators x1, . . . , x,, spanned by monomials p = {ml, . . . ,<br />

13. 185

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