Free binary decision diagrams (FBDDs) are graph-based data structures representing Boolean functions with a constraint (additional to binary decision diagrams) that each variable is tested at most once during the computation. The function EAR_n is the following Boolean function defined
for n x n Boolean matrices: EAR_n(M)=1 iff the matrix M contains two equal adjacent rows. We prove that each FBDD computing EAR_n must have size
at least 2^{0.63 log_2^2 n-O(log n loglog n)} and we present a construction of such diagrams of size 2^{1.89 log_2^2 n+O(log n)}.