関税と貿易に関する一般協定 かんぜいとぼうえきにかんするいっぱんきょうてい General Agreement on Tariffs and Trade (abolished in 1995); GATT n Advanced ➥
四色定理 ししょくていり よんしょくていり four-color theorem (colour) (theorem stating that any map can be colored such that no two adjacent segments have the same color, if only four colors are used) n Advanced ➥