Invariants for metabelian groups of prime power exponent, colorings and stairs

We study the free metabelian group $M(2,n)$ of prime power exponent $n$ on two generators by means of invariants $M(2,n)'\to \mathbb{Z}_n$ that we construct from colorings of the squares in the integer grid $\mathbb{R} \times \mathbb{Z} \cup \mathbb{Z} \times \mathbb{R}$. In particular we improve bounds found by M.F. Newman for the order of $M(2,2^k)$. We study identities in $M(2,n)$, which give information about identities in the Burnside group $B(2,n)$ and the restricted Burnside group $R(2,n)$.Comment: 29 pages, 16 figure

The 2-generator restricted burnside group of exponent 7

We report on our construction of a power-commutator presentation for R(2, 7), the largest finite 2-generator group of exponent 7. Our calculations show that R(2, 7) has order 720416, nilpotency class 28, and derived length 5. The calculations also imply that the associated Lie ring of R(2, 7) satisfies relations which are not consequences of the multilinear identities which hold in the associated Lie rings of groups of exponent 7