Kre-O Kre-O KRE-O is a line of construction toys (similar to Lego and Mega Bloks) manufactured by South Korea-based Oxford and marketed by Hasbro. Kre-O was released in stores in Fall 2011. The name "Kre-O" comes from the Latin word "creo", which means "I create". Kre-O toys feature highly articulated humanoid figures called Kreons. Kre-O blocks are compatible with Lego bricks, hence also compatible with Mega Bloks and other building block brands. Kre-O "Transformers" is the first line of the Kre-O series. They were first shown in February 2011 at the American International Toy Fair trade show in New York. Transformers
K-set (geometry) "O"("nk") upper bound holds for counting the number of different minimum spanning trees formed in a graph with "n" edges and "k" vertices, when the edges have weights that vary linearly with a parameter λ. This parametric minimum spanning tree problem has been studied by various authors and can be used to solve other bicriterion spanning tree optimization problems. However, the best known lower bound for the parametric minimum spanning tree problem is Ω("n" α("k")), where α is the inverse Ackermann function, an even weaker bound than that for the "k"-set problem. For more general matroids, Dey's "O"("nk") upper bound