Complex sentence: In 1998, Daniel J. Bernstein showed that 391909274215699968 ≥ Ta (6) ≥ 10 18, and in 2002, Randall L. Rathbun gave proof that Ta (6) ≤ 24153319581254312065344.
Split into simpler sentences: In 1998, Daniel J. Bernstein showed that a lower bound was Ta (6) ≥ 391909274215699968. In 2002, Randall L. Rathbun improved the upper bound to Ta (6) ≤ 24153319581254312065344.