Chess Problem Solver Solves a given chess position

Chess Problem Solver • Solves a given chess position for checkmate • Problem input in text format

Problem Characteristics • Search tree solving method • Very large computation • Low communication requirement

Parallel Architecture • • • Message passing using PVM Master/Slave processes Distributed task queues Coarse grain tasks Designed for future flexibility

Implementation Strategy • Basic data unit • Basic software function • Tree search routine

Basic Data Unit: “Problem” • Contains all necessary information about the state of a position – Status of pieces on board – Whose turn to move – What player to solve the problem for – Maximum levels to search – The move that was made to get there

Basic Software Function • Breaks down a given problem using all possible moves. • Generates a new list of problems. • Is used to create the branches in the search tree.

Search Routine • Examines a problem and determines the necessary action. • There are two possibilities: – the problem represents an end node • the node represents a possible solution • the node does not represent a possible solution • the problem is incomplete and the search levels have been exhausted – further investigation is necessary • break down the problem

Master Process Requirements • Input initial problem and break down into list of tasks • Determine the necessary number of slaves • Spawn the slave processes • Send tasks to slaves • Compile results obtained from slaves • Terminate the slaves when complete

Slave Process Requirements • Wait for command from master (solve problem, transfer work, or terminate) • On solve problem command, solve the problem and return results to the master • On transfer work message, send work to another slave process • Terminate message kills the slave process.

Possible Enhancements • Assign processors to a number of groups • Each group will have its own master (determined by lowest TID for example) • Assign a task to each group • Will cut down on communication to/from the master which cuts down stalled tasks • Only necessary for a large number of processors when using coarse grain strategy