Optimization system and control method thereof

An optimization system control method comprising:

• dividing, by a control apparatus, a plurality of weight coefficients into n (n is an integer of 2 or more) weight coefficient groups in such a manner that each of the n weight coefficient groups includes weight coefficients about at least two bits and storing corresponding one of the n weight coefficient groups in a storage device of each of n optimization apparatuses different each other in an optimization system, the plurality of weight coefficients each indicating a magnitude of an interaction between a pair of bits among all bits corresponding to all spins included in an Ising model obtained by converting a calculation target problem;
• and
• controlling, by the control apparatus, size of a temperature parameter on the optimization system,
• wherein the optimization system includes the n optimization apparatuses and a second selection circuit,
• wherein each of the n optimization apparatuses includes:
• the storage device that holds the corresponding one of the n weight coefficient groups obtained by dividing the plurality of weight coefficients;
• a bit value calculation circuit that calculates, for each of the at least two bits, an energy change of the Ising model that occurs when one of the at least two bits changes, based on the corresponding one of the n weight coefficient groups, a value of an updated bit that has been updated among all the bits, and first identification information that identifies the updated bit, determines whether to accept updating about each of the at least two bits based on a magnitude relationship between a thermal excitation energy determined based on a random number and the temperature parameter and the energy change, and outputs flag information that indicates a determination result of whether to accept the updating and an updated value of an accepted bit whose update has been accepted among the at least two bits;
• and a first selection circuit that selects one accepted bit based on the flag information and outputs a state signal that includes the flag information about the one accepted bit selected, the updated value, and second identification information that identifies the one accepted bit selected,
• wherein each of the n optimization apparatuses outputs the state signal based on the corresponding one of the n weight coefficient groups that differs among the n optimization apparatuses, and
• wherein the second selection circuit determines the updated bit based on the flag information included in the state signal outputted by the first selection circuit of each of the n optimization apparatuses and supplies the value of the updated bit and the first identification information that identifies the updated bit to the each of the n optimization apparatuses.

A non-transitory computer-readable recording medium storing therein an optimization system controlling program that causes a computer to execute a process comprising:

• dividing a plurality of weight coefficients into n (n is an integer of 2 or more) weight coefficient groups in such a manner that each of the n weight coefficient groups includes weight coefficients about at least two bits and storing corresponding one of the n weight coefficient groups in a storage device of each of n optimization apparatuses different each other in an optimization system, the plurality of weight coefficients each indicating a magnitude of an interaction between a pair of bits among all bits corresponding to all spins included in an Ising model obtained by converting a calculation target problem;
• and
• controlling size of a temperature parameter on the optimization system,
• wherein the optimization system includes the n optimization apparatuses and a second selection circuit,
• wherein each of the n optimization apparatuses includes:
• the storage device that holds the corresponding one of the n weight coefficient groups obtained by dividing the plurality of weight coefficients;
• a bit value calculation circuit that calculates, for each of the at least two bits, an energy change of the Ising model that occurs when one of the at least two bits changes, based on the corresponding one of the n weight coefficient groups, a value of an updated bit that has been updated among all the bits, and first identification information that identifies the updated bit, determines whether to accept updating about each of the at least two bits based on a magnitude relationship between a thermal excitation energy determined based on a random number and the temperature parameter and the energy change, and outputs flag information that indicates a determination result of whether to accept the updating and an updated value of an accepted bit whose update has been accepted among the at least two bits;
• and a first selection circuit that selects one accepted bit based on the flag information and outputs a state signal that includes the flag information about the one accepted bit selected, the updated value, and second identification information that identifies the one accepted bit selected,
• wherein each of the n optimization apparatuses outputs the state signal based on the corresponding one of the n weight coefficient groups that differs among the n optimization apparatuses, and
• wherein the second selection circuit determines the updated bit based on the flag information included in the state signal outputted by the first selection circuit of each of the n optimization apparatuses and supplies the value of the updated bit and the first identification information that identifies the updated bit to the each of the n optimization apparatuses.