We introduce the concepts of semi-open sets and semi-continuous functions, and discuss some of their properties in fuzzifying topology.

给出了不分明化拓扑空间中半开集和半连续函数的概念，并讨论了它们的某些性质。

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In their last meeting, Djokovic saved two match points as he came from two sets down to beat Federer in the US Open semi-finals.

在他们的上次交手——美网半决赛上，德约科维奇在两盘落后的局面下挽救两个赛点而击败费德勒。

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Next to Paris where the world number one Rafael Nadal is through to the semi-finals of the French Open tennis after a straight-sets win over Robin Soderling.

下面让我们转到巴黎，在直下三盘击败罗宾•索德林后，世界网球男子头号选手拉斐尔·纳达尔进入了法网公开赛半决赛。在半决赛的四人中，纳达尔将面对安迪·穆雷。

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However, Djokovic beat Federer in straight sets the last time they met at the Australian Open, in the semi-finals in 2008.

BBC: Novak Djokovic makes short work of Berdych in Melbourne

His 2001 Wimbledon semi-final against Goran Ivanisevic, when he was two sets to one up, and his 2002 Australian Open fourth-round defeat to Jonas Bjorkman, when the draw had opened up for Henman, are two of too many examples.

BBC: SPORT | Tennis | Henman promises so much more