Hill Climbing Lecture 8 PDF

Hill Climbing Prof. Dr. Magdy Zakarya Dr. Dina Saif A heuristic technique refers to an approach for problem-solving that uses practical methods to find solutions more quickly when traditional methods are too slow or inefficient. These techniques focus on obtaining approximate solutions rathe...

Hill Climbing Prof. Dr. Magdy Zakarya Dr. Dina Saif A heuristic technique refers to an approach for problem-solving that uses practical methods to find solutions more quickly when traditional methods are too slow or inefficient. These techniques focus on obtaining approximate solutions rather than perfect outcomes.  Hill climbing types Steepest- Simple Stochastic Ascent  Simulated Annealing A hill-climbing algorithm which never makes a move towards a lower value guaranteed to be incomplete because it can get stuck on a local maximum. And if algorithm applies a random walk, by moving a successor, then it may complete but not efficient. Simulated Annealing is an algorithm which yields both efficiency and completeness. In mechanical term Annealing is a process of hardening a metal or glass to a high temperature then cooling gradually, so this allows the metal to reach a low-energy crystalline state. The same process is used in simulated annealing in which the algorithm picks a random move, instead of picking the best move. If the random move improves the state, then it follows the same path. Otherwise, the algorithm follows the path which has a probability of less than 1 or it moves downhill and chooses another path.  20 Simulated Annealing ▪ A probabilistic algorithm for global optimization ▪ Introduced by Kirkpatrick, Gelatt and Vecchi in 1983 and V. Černy in 1985. ▪ Inspired by the manner in which liquids freeze or metals and glass crystallize in the process of annealing ▪ Basic inspiration: What is annealing? ▪ In metallurgy, annealing is the physical process used to temper or harden metals or glass by heating them to a high temperature and then gradually cooling them, thus allowing the material to coalesce into a low energy crystalline state.  21 ❖Simulated Annealing Heating then slowly cooling a substance to obtain a strong cristalline structure. Key idea: Simulated Annealing combines Hill Climbing with a random walk in some way that yields both efficiency and completeness. ▪ escape local maxima by allowing some "bad" moves but gradually decrease their frequency 22