It is an object of the present invention to provide a program that can simply input dependency of tasks.The first aspect of the invention relates to a program, especially relates to a higher level language. The program requires only inputs regarding tasks and dependency. Then the program may decide all tasks and dependency such that it can schedule all of the tasks with error-free. After all the tasks are scheduled using the dependency determined using the program of the invention. Each task may be executed by means of other programs or hardware.