CylindricalDecomposition[ineqs, {x1, x2, ...}]把不等式 ineqs 表示的区域分解为柱形部分，其方向依次对应于 .
找出单位盘的柱形分解：
Reduce Resolve FindInstance Discriminant Resultant SemialgebraicComponentInstances GenericCylindricalDecomposition GroebnerBasis FullSimplify
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