Group theory is a powerful formal method for analyzing abstract and physical systems in which (a • x = b) always has a unique solution. The theory does not concern itself with what a and b actually are nor with what the operation symbolized by • actually is. By taking this abstract approach group theory deals with many mathematical systems at once. Group theory requires only that a mathematical system obey a few simple rules. The theory then seeks to find out properties common to all systems that obey these few rules.