Slicing floorplan
Beginner
A layout you can make by cutting a rectangle in two again and again, with each cut going all the way across.
Novice
A layout you can build by repeatedly cutting a rectangle in two with straight cuts that run all the way across it. It can be stored as a tree whose branches are cuts and whose leaves are blocks.
Expert
Represented by slicing trees or Polish expressions and often searched with simulated annealing. Cheap to evaluate, since block shape functions combine up the tree and give the minimum area in polynomial time, but it cannot represent non-slicing packings, in which no straight cut crosses the whole layout without splitting a block.