Simulated annealing
Beginner
A way to search for a good layout by trying random swaps, and sometimes keeping a worse one early on to get out of a dead end.
Novice
A search method that tries random changes, always keeps improvements, and sometimes keeps a change that makes things worse, with a probability that shrinks as a “temperature” setting is lowered. Early on it explores freely; later it only accepts improvements.
Expert
Propose a move, accept it if cost falls, otherwise accept with probability , and lower geometrically. The basis of TimberWolf, the classic annealing placer of the 1980s. Quality can be high, but it converges slowly and scales poorly to millions of cells.
Explained in Placement (Design Flow).