  The operation of binary intermolecular recombination, originating in the
theory of DNA computing, permits a natural generalization to n-ary operations
which perform simultaneous recombination of n molecules. In the case n = 3, we
use computer algebra to determine the polynomial identities of degree <= 9
satisfied by this trilinear nonassociative operation. Our approach requires
computing a basis for the nullspace of a large integer matrix, and for this we
compare two methods: (i) the row canonical form, and (ii) the Hermite normal
form with lattice basis reduction. In the conclusion, we formulate some
conjectures for the general case of n-ary intermolecular recombination.
