Die Another Day
Die Another Day
复制标题
择日而死
DOI：
10.1007/s00224-008-9109-y
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发表时间：
2007
影响因子：
0.5
通讯作者：
R. Fleischer
中科院分区：
文献类型：
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作者：
R. Fleischer
九头蛇是希腊神话中的一种多头怪物，它会立即用一两个新的头取代被砍掉的头。杀死这个怪物是赫拉克勒斯的第二个任务。在抽象的意义上，Hydra可以被建模为一棵树，其中叶子是头，当头被切断时，一些子树会被复制。不同的水螅种类在不同的子树可以复制的多样性方面有所不同。运用一些深奥的数学，已经证明了两类九头蛇物种必须永远死亡，而与头被砍掉的顺序无关。在本文中，我们确定了三个性质的水螅是必要的和足够的，使它不朽或迫使它死亡。我们也给出了一个简单的组合证明这种分类。如果赫拉克勒斯知道这件事...
The Hydra was a many-headed monster from Greek mythology that would immediately replace a head that was cut off by one or two new heads. It was the second task of Hercules to kill this monster. In an abstract sense, a Hydra can be modeled as a tree where the leaves are the heads, and when a head is cut off some subtrees get duplicated. Different Hydra species differ by which subtress can be duplicated in which multiplicity. Using some deep mathematics, it had been shown that two classes of Hydra species must always die, independent of the order in which heads are cut off. In this paper we identify three properties for a Hydra that are necessary and sufficient to make it immortal or force it to die. We also give a simple combinatorial proof for this classification. Now, if Hercules had known this…
弱科尼格引理蕴涵布劳威尔扇形定理：直接证明
DOI：
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发表时间：
2006
期刊：
Notre Dame J. Formal Logic 47
影响因子：
--
作者：
H.Ishihara
通讯作者：
H.Ishihara