two attacks the pair, the player who initiated the wedge can place a stone to immediately counter by capturing a different pair elsewhere on the board. Extension Extension is a tactic used to force captures. Rather than extending a bound tria into a tessera to force the opponent to respond by blocking it, it is sometimes beneficial to "extend" the tria into what's called a "stretch" tessera. A stretch tessera is a line of three stones of one color broken by an empty space followed by another stone of the same color. If the opponent doesn't block or dismantle the stretch tessera, then the player who formed it can create a pente on the next turn. Extension into a stretch tessera is used because of how stones are aligned to the side of the line. If an opponent's stone is lined up so that when another of their stones is placed in the empty space to block, and it forms a pair, this pair can then be captured. Stretch trias can be utilized for this tactic as well so long as they're unbound and threaten to form an open tessera. Notation There are two notation systems developed for Pente. USPA The older notation system was used by the USPA for its newsletters and documentation of tournament games. The notation system was based on an xy 2 dimensional grid used in mathematics. The center of the board was notated as "0". Points on the board were measured based on their distance and direction from the center. The four cardinal directions were notated as L, R, U, D for Left, Right, Up, Down, while the number of spaces in any of the directions were notated by a number signifying the empty intersections away from "0." A stone two intersections right and seven intersections up would be recorded as R2U7. If a stone was on the same vertical or horizontal axis as the center point, then the "0" would be left off of the notation. A stone two intersections up from center and zero intersections left or right would be notated simply as U2. Capture moves were notated by placing an asterisk following the notation for the stone's location. For organization, moves were recorded as sets with white's ply on the left and black's ply on the right, and numbered in ascending order according to when they happened in the game. Modern The