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  "body": "\n## Summary\n\nA quasiconvex function is a real function on a convex set whose sublevel sets are all [[convex|02AS45T3H9]].\nEvery [[convex function|07Q7CNM5WF]] is quasiconvex, but many quasiconvex functions are not convex.\nThe notion is used in optimization and economics, where only the shape of the sublevel sets matters, not the exact values.\nThe [[definition|393PNMXBFJ]] gives the precise condition.\n\n## Explanations\n\n### L1 human\n\nA function is quasiconvex if, on each segment, its value never rises above the larger of the two values at the ends.\nPicture a valley whose sides may be steep or flat but never have a bump in the middle.\nEvery increasing function on the real line is quasiconvex, even if its graph bends downward.\nFor example $\\sqrt{\\abs{x}}$ is quasiconvex on $\\R$ but not convex.\n",
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