A computer program and related data processing methods adapted for computational decision-making including a graphical programming interface, a data structure and a program execution engine. The program uses a hierarchical structure of positions and arguments along with linkages which define functional relationships between different positions and arguments. The positions are primarily characterized by position values that may represent outputs although the positions also have other functional features. The arguments are characterized by argument values that may represent inputs. The values of the arguments are associated with each position are combined to determine the value of that position. A data structure is utilized that is comprised of position and argument data tables and a linkage data structure including data arrays associated with each type of linkage. The position and argument data tables store basic position and argument data such as value. The data arrays of the linkage data structures store the basic data entries by linkage type specifying the linkage connections and in accordance with index values that may be used in identifying the data entries.