单连通性

Poincaré, almost a hundred years ago, knew that a two dimensional sphere is essentially characterized by this property of simple connectivity, and asked the corresponding question for the three dimensional sphere (the set of points in four dimensional space at unit distance from the origin).

大 约在一百年以前，庞加莱已经知道，二维球面本质上可由单连通性来刻画，他提出三维球面（四维空间中与原点有单位距离的点的全体）的对应问题。

The sand bodies of the inner delta front are from under water distributary channels and under water crevasse splays, the former is good at the physical property and has a good single pass connectivity, and the latter has a high independence and can form a suit of fake- connected sand body.

内前缘主要发育水下分流河道和水下决口扇砂体，前者物性好、单向连通性好，后者单期独立性强，多期叠置后可形成砂体连片假象；外前缘砂体连片性非常强，但是砂体内部发育大量水平或近水平泥质薄层，储层的垂向非均质性较强。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。