Neighborhood closure: implement an algorithm that calculates the neighborhood closure for any object or attribute of a formal context, i.e., the set of objects and attributes that belong to the same component of the lattice (after horizontal decomposition) as the original object or attribute. It is easy to determine the sets visually from the line diagram of the lattice. But it is not so easy to write an efficient algorithm that calculates these sets for formal contexts of the size of RT (i.e., which have hundreds of thousands objects and attributes). For further information:

[Priss and Old, 2006] provide more background on neighborhood closure lattices. [P,!]