Nonexistence of a few binary orthogonal arrays
  We develop and apply combinatorial algorithms for investigation of the feasible distance distributions of binary orthogonal arrays with respect to a point of the ambient binary Hamming space utilizing constraints imposed from the relations between the distance distributions of connected arrays. This turns out to be strong enough and we prove the nonexistence of binary orthogonal arrays of parameters (length, cardinality, strength)$\ =(9,6.2^4=96,4)$, $(10,6.2^5,5)$, $(10,7.2^4=112,4)$, $(11,7.2^5,5)$, $(11,7.2^4,4)$ and $(12,7.2^5,5)$, resolving the first cases where the existence was undecided so far. For the existing arrays our approach allows substantial reduction of the number of feasible distance distributions which could be helpful for classification results (uniqueness, for example). 
Peter Boyvalenkov, Tanya Marinova, Maya Stoyanova
cs.IT math.IT