I point out that there is a nice method of John Dixon for exact computation with cyclotomic integers by working over a well chosen finite field F_p.
For algebraic integers there is the example of Darmon, Ford for reconstructing exact values using p-adics. This is in Comm in Algebra 17, (1989). Lattice reduction may also be used. John McKay _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
