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lower half plane：下半平面

lower envelope 下包絡(luò) | lower half plane 下半平面 | lower integral 下積分

lower envelope：下包絡(luò)

lower dini derivative 狄尼下導(dǎo)數(shù) | lower envelope 下包絡(luò) | lower half plane 下半平面

upper envelope：上包絡(luò)

upper derivative 上導(dǎo)數(shù) | upper envelope 上包絡(luò) | upper half plane 上半平面