Consider an infinite binary search tree in which the branches have independent random costs. Suppose that we must find an optimal (cheapest) or nearly optimal path from the root to a node at depth n. Karp and Pearl [1983] show that a bounded-lookahead backtracking algorithm A2 usually finds a nearly optimal path in linear expected time (when the costs take only the values 0 or 1). From this suc...

Heuristics are crucial tools in decreasing search effort in varied fields of AI. In order to be effective, a heuristic must be efficient to compute, as well as provide useful information to the search algorithm. However, some well-known heuristics which do well in reducing backtracking are so heavy that the gain of deploying them in a search algorithm might be outweighed by their overhead. We p...

Because of their occasional need to return to shallow points in a search tree, existing backtracking methods can sometimes erase meaningful progress toward solving a search problem. In this paper, we present a method by which backtrack points can be moved deeper in the search space, thereby avoiding this di culty. The technique developed is a variant of dependency-directed backtracking that use...

The most advanced implementation of adaptive constraint processing with Constraint Handling Rules (CHR) allows the application of intelligent search strategies to solve Constraint Satisfaction Problems (CSP). This presentation compares an improved version of conflict-directed backjumping and two variants of dynamic backtracking with respect to chronological backtracking on some of the AIM insta...

Real-time heuristic search algorithms are suitable for situated agents that need to make their decisions in constant time. Since the original work by Korf nearly two decades ago, numerous extensions have been suggested. One of the most intriguing extensions is the idea of backtracking wherein the agent decides to return to a previously visited state as opposed to moving forward greedily. This i...

There has been substantial recent interest in two new families of search techniques. One family consists of systematic approaches, which use the idea of dependency directed backtracking (DDB) and dynamic backtracking (DB) as an antidote for the inefficiencies of chronological backtracking. Based on backtracking, systematic approaches are able to produce an optimal assignment, when no time limit...

Recent works on constraint relaxation [Jussien, 1997; Jussien and Boizumault, 1997b] provided the decorum system (Deduction-based Constraint Relaxation Management). That system can be seen as an integration of arc-consistency within the dynamic backtracking algorithm [Ginsberg, 1993]. Dynamic backtracking replaces the backtracking process by a much less blind behavior that consists in local mod...

Routers must perform packet classification at high speeds to efficiently implement functions such as firewalls and diffserv. Classification can be based on an arbitrary number of fields in the packet header. Performing classification quickly on an arbitrary number of fields is known to be difficult, and has poor worst-case complexity. In this paper, we re-examine two basic mechanisms that have ...