A decision functional for multitime controllability
  This paper investigates the multitime linear normal PDE systems. We study especially the controllability of such systems, obtaining complementary results to those in our recent papers. Here the multitime controllability original results are formulated using the $\gamma$ - gramian matrix, the Im - gramian space and a controllability functional. There are given also some original examples which illustrate and round the theoretical results. 
Cristian Ghiu and Constantin Udriste
math.OC