Markovian semigroup from non-Markovian evolutions
  It is shown that a convex combination of two non-Markovian evolutions may lead to Markovian semigroup. This shows that convex combination of quantum evolutions displaying nontrivial memory effects may result in a perfectly memoryless evolution. 
F. A. Wudarski and D. Chru\'sci\'nski
quant-ph