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...

In this paper, a new search technique over numeric csps is presented: dynamic domain splitting. The usual search technique over numeric csps is a dichotomic search interleaved with a consistency ltering, which is called domain splitting. This paper proposes to replace chronological backtracking at the core of domain splitting by a non destructive backtracking technique.

The algorithm for constraint-satisfaction problems, Probe Order Backtracking, has an average running time much faster than any previously analyzed algorithm under conditions where solutions are common. The algorithm uses a probing assignment (a preselected test assignment to unset variables) to help guide the search for a solution. If the problem is not satisfied when the unset variables are te...

Modern Chaff-like SAT solvers enhance plain backtracking (DLL) by Conflict-Driven Learning (CDL), including 1UIP-based Conflict-Directed Backjumping (CDB), Non-Chronological Backtracking (NCB), and 1UIP-based Conflict-Clause Recording (CCR). We show how to add these enhancements step-by-step to plain DLL to derive Chaff’s Conflict-Driven Learning algorithm, separately and independently of BCP, ...

Efficient utilization of time and effort is essential in Personnel scheduling problems to evenly balance the workload among the people and attempt to satisfy the personnel preferences. In Constraint Satisfaction Problem based scheduling problems, when a branch of the search fails the backtracking search algorithm back up to the preceding variable and try a different value for it. So here the mo...

A non-backtracking walk on a graph, H , is a directed path of directed edges of H such that no edge is the inverse of its preceding edge. Non-backtracking walks of a given length can be counted using the non-backtracking adjacency matrix, B, indexed by H ’s directed edges and related to Ihara’s Zeta function. We show how to determine B’s spectrum in the case where H is a tree covering a finite ...

In recent work with Vincent Danos and Jean Krivine the author introduced a general framework for backtracking in concurrent formalisms, thus allowing modelling of situations where deadlock can arise without the necessity of explicitly encoding the often involved backtracking mechanisms. Here we shall discuss how the framework can be applied to the well-known formalism of double-pushout graph tr...