In 2002, he and his research group managed to solve a 'nontrivial' problem using DNA computation. Specifically, they solved a 20-variable SAT problem having more than 1 million potential solutions. They did it in a manner similar to the one Adleman used in his seminal 1994 paper. First, a mixture of DNA strands logically representative of the problem's solution space was synthesized. This mixture was then operated upon algorithmically using biochemical techniques to winnow out the 'incorrect' strands, leaving behind only those strands that 'satisfied' the problem. Analysis of the nucleotide sequence of these remaining strands revealed 'correct' solutions to the original problem.