An extension of process algebra for modelling processes with backtracking is introduced. This extension is semantically based on processes that transform data because, in our view, backtracking is the undoing of the eeects caused by a process in some initial data-state if this process fails. The data-states are given by a data environment, which is a structure that also deenes in which data-sta...

The cost of backtracking has been identified as one of the bottlenecks in achieving peak performance in compiled Prolog programs. Much of the backtracking in Prolog programs is shallow, i.e. is caused by unification failures in the head of a clause when there are more alternatives for the same procedure, and so special treatment of this form of backtracking has been proposed as a significant op...

An execution backtracking facility in interactive source debuggers allows users to mirror their thought processes while debugging — working backwards from the location where an error is manifested and determining the conditions under which the error occurred. Such a facility also allows a user to change program characteristics and reexecute from arbitrary points within the program under examina...

Beam searches are a very effective algorithm for solving problems that prove intractable to complete algorithms like weighted A* and greedy search. Unfortunately, the inadmissible pruning that is the hallmark of a beam search makes the algorithm incomplete. Existing complete extensions to beam search expand pruned nodes systematically according to generation order. Selecting pruned nodes to exp...

In the last years, the AI community has shown an increasing interest in distributed problem solving. In the scope of distributed constraint reasoning, several asynchronous backtracking procedures have been proposed for finding solutions in a constraint network distributed among several computers. They differ in the way they store failing combinations of values (nogoods), and in the way they che...

Almost ten years ago, Ralf Hinze has written a functional pearl on how to derive backtracking functionality for the purely functional programming language Haskell. In these notes, we show how to arrive at the efficient, two-continuation based backtracking monad derived by Hinze starting from an intuitive inefficient implementation that we subsequently refine using well known program transformat...

A backtracking algorithm with element order selection is presented, and its efficiency discussed in relation both to standard examples and to examples concerning relation-preserving maps which the algorithm was derived to solve.

In the scope of distributed constraint reasoning, the main algorithms presented so far have a feature in common: the addition of links between previously unrelated agents, before or during search. This paper presents a new search procedure for finding a solution in a distributed constraint satisfaction problem. This algorithm makes use of some of the good properties of centralised dynamic backt...