1. A method of operation of an arithmetic and logic unit for solving a problem including a series of decisions having an order dependency by creating a model by a binary tree using processings for decisions not having dependency input/outputs as leaves and using processings for determination of a higher priority as nodes other than the leaves, in said method of operation of an arithmetic and logic unit, processings for decisions not having dependency input/outputs, corresponding to the decisions, each executing a predetermined decision based on a single or a plurality of data inputs comprising an R-nary number or quantity of logical value information at a point of time when said data input becomes valid and outputting a code of a format combining into one an indeterminate code "Q" of the meaning "cannot be defined" and the quantity as a working conclusion; said processings for determination of higher priorities, corresponding to the series of decisions, each receiving as its input the working conclusions of two processings for decisions not having dependency input/outputs or the working conclusions of two processings for determination of higher priorities before the same, outputting the working conclusion of the processing for a decision of a higher significant bit not having a dependency input/output or the working conclusion of the processing for determination of a higher priority of a higher significant bit as a working conclusion when the working conclusion of the processing for a decision not having a dependency input/output of a higher significant bit or the working conclusion of the processing for determination of a higher priority of a higher significant bit is not the indeterminate code "Q", and outputting the working conclusion of the processing for a decision not having a dependency input/output of a lower significant bit or the working conclusion of the processing for determination of a higher priority of a lower significant bit as the working conclusion when the working conclusion of the processing for a decision not having a dependency input/output of a higher significant bit or the working conclusion of the processing for determination of a higher priority of a higher significant bit is the indeterminate code "Q"; and all processings for decisions serving as leaves of the binary tree and all processings for determination of higher priorities located at the same depth in the binary tree being respectively processed in parallel and the working conclusion of the processing for determination of a higher priority serving as a root of the binary tree being defined as the conclusion of the problem.