Carillon century in the Low Countries. The first carillon was in Flanders, where a "fool" performed music on the bells of Oudenaarde Town Hall in 1510 by using a baton keyboard. Major figures in the evolution of the modern carillon were Pieter and François Hemony working in the 17th century. They are credited as being the greatest carillon bell founders in the history of the Low Countries. They developed the carillon, in collaboration with Jacob van Eyck, into a full-fledged musical instrument by casting the first tuned carillon in 1644, which was installed in Zutphen's Wijnhuistoren tower. The World Carillon Federation
Partition of a set "coarser" than "α"—if every element of "α" is a subset of some element of "ρ". Informally, this means that "α" is a further fragmentation of "ρ". In that case, it is written that "α" ≤ "ρ". This "finer-than" relation on the set of partitions of "X" is a partial order (so the notation "≤" is appropriate). Each set of elements has a least upper bound and a greatest lower bound, so that it forms a lattice, and more specifically (for partitions of a finite set) it is a geometric lattice. The "partition lattice" of a 4-element set has 15 elements