 Complete the following phrase:  Theoreticians describe many elementary tactical methods and typical maneuvers, for example: pins, forks, skewers, batteries, discovered attacks especially discovered checks, zwischenzugs, deflections, decoys, sacrifices, underminings, overloadings, and interferences. Simple one-move or two-move tactical actions  threats, exchanges of , and double attacks  can be combined into more complicated sequences of tactical maneuvers that are often forced from the point of view of one or both players. A forced variation that involves a sacrifice and usually results in a tangible gain is called a combination. Brilliant combinations  such as those in the 