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Some basic properties of σ- LFSR over F4 are studied, such as nonlinearity, cycle structure distribution of state graph, the largest period and counting problem related. The conclusions are as follows:The coefficient ring of σ-LFSR is isomorphic to the matrix ring over F,. The cycle structure of σ- LFSR is consistent with that of the determinant of the corresponding polynomial matrix if and only if the feedback polynomial of - LFSR does not contain nontrivial factor over F2,. The counting formula of the number of σ- LFSR with inconsistent cycle structure is also showed in that part. The period of σ-LFSR with degree n is maximum if and only if the determinant of the corresponding polynomial matrix is the primitive polynomial with order 2n over F2,.

本文研究了有限域F_4上的σ-LFSR的一些基本性质，如非奇异性、状态图的圈结构的分布、最大圈的充要条件及相关的计数问题等，得到以下结论：σ-LFSR的系数环同构于F_2上的矩阵环；σ-LFSR的状态图的圈结构与对应的多项式矩阵的行列式的圈结构一致的充要条件为σ-LFSR的反馈多项式不含有非平凡的F_2上的因式，给出了圈结构不一致的σ-LFSR的计数公式； n次σ-LFSR周期达到最大，当且仅当对应多项式矩阵的行列式为F_2上的2n次本原多项式。

Many scholars have studied these respects and given many important results, for example, the Hupperts famous theorem, namely, a finite group G is supersolvable if and only if every maximal subgroup of G has prime index; a finite group G is nilpotent if and only if every maximal subgroup of G is normal in G; a finite group G is solvable if and only if every maximal subgroup of G is c-normal in G (See it in [70]); etc.

很多学者都在这些方面进行了研究，得到了很多重要的结果，如：著名的Huppert定理，即有限群为超可解当且仅当它的所有极大子群的指数为素数；有限群为幂零当且仅当每个极大子群都正规；有限群为可解当且仅当它的极大子群均c-正规(见[70])；等等。

In this paper, the following statements were proved: is chaintransitive if and only if is chaintransitive; if a homeomorphism is a Lipschitz map, then has the average shadowing property if and only if has the average shadowing property.

设是紧致度量空间，：X→X是连续的，n为任一给定的正整数，证明了：是链可迁的当且仅当是链可迁的；若同胚是Lipschitz映射，则有平均跟踪性当且仅当有平均跟踪性。

In the last chapter, on the basis of theories in paper [4, 5], the notions of strong mixing, weak mixing, generator and expansion of the variable-parametric dynamical system are introduced, it turns out that in variable-parametric dynamical system strong mixing implies weak mixing and then implies transitivity; it is proved that if and both are variable-parametric dynamical system, F conjugates with G , the members of F are communicate with each other and the members of G are also communicate with each other, what's more, they are both homeomorphism, then F is strong mixing implies G has the same properties; futhermore, we prove that F is strong mixing implies F Devaney chaos in the sense of modification in variable-parametric dynamical system and that F Devaney chaos in the sense of modification if and only if G Devaney chaos in the sense of modification when semi-conjugate with and they both are communicate and homeomorphism; at last, we illustrate that F has generator if and only if it has weak generator, and we also prove that if F is expansion, then F has generator.

在第三章中，我们在文[4，5]的基础上，提出了变参数动力系统拓扑强混合、拓扑弱混合以及变参数动力系统的生成子、扩张的概念；证明了变参数动力系统拓扑强混合蕴含拓扑弱混合，进而蕴含拓扑传递；证明了：如果，为两个变参数动力系统，F与G拓扑半共轭，且F两两可交换，G两两可交换，它们均为同胚映射，那么F拓扑强混合，则G也有同样的性质；本章还证明了变参数动力系统拓扑强混合蕴含F在修改的意义下Devaney混沌；在此基础上得出了：如果变参数动力系统与变参数动力系统拓扑半共轭，它们都两两可交换，并且它们均为同胚映射，那么F在修改的意义下Devaney混沌当且仅当G在修改的意义下Devaney混沌；得出了F有生成子当且仅当F有弱生成子；如果F是扩张的，则F有生成子。

R is a regular ring if and only if every singular right R-module is P-flat if and only if every cyclic singular right R-module is P-flat if and only if the homomorphic image of every P-flat right R-module is P-flat.

得到了R为正则环当且仅当每一个奇异右R-模P-平坦当且仅当每一个循环奇异右R-模P-平坦当且仅当P-平坦右R-模的同态像P-平坦这一主要结果。

The following statements are proved:. A is equivalent to a diagonal matrix if and only if A is similar to a diagonal matrix.. If R is an APT ring, then A can be uniquely diagonalized as diag{e1,..., en} and ei divides ei+1.. R is an APT ring if and only if R/I is an APT ring, where I is a nilpotent ideal of R.

本文证明了以下结果：A相抵于一对角阵当且仅当A相似于一对角阵；若R是一APT环，则A在相似变换之下可唯一地化为对角形diag{e1，…，en｝，这里ei整除ei+1；R是APT环当且仅当R/I是APT环，这里I是环R的一幂零理想。

In Particular, we prove that N is the equality relation on S if and only if S is a semilattice and N is the universal relation on S if and only if 5 is the only principal filter.

其次，证明了N是偏序半群S中的恒等关系当且仅当S是一个半格，N是偏序半群S中的泛关系当且仅当S自身是S中唯一的主滤子。

Finally, it shows that R is von Neumann regular ring if and only if every right .R-module is right pm-injective if and only if every right principal right ideal of R is right pm-injective if and only if every essential right ideal of R is right pm-injective. Furthermore, some good properties are obtained.

最后，得到R是von Neumann正则环当且仅当每个右R-模是右pm-内射当且仅当R的每个主右理想是右pm-内射当且仅当R的每个本质右理想是右pm-内射，以及其他诸多好的性质。

The document was not found in the cache, or it required -revalidation prohibited by only-if-cached directive.

而所要的文件并未存在于本缓存服务器中，或者这个连结请求需要刷新文件而- only-if-cached 指令禁止这么做。

But such innovations will happen only if national governments can be discouraged from stamping the commission's proposals "return to sender".

但是只有在各国政府能被劝阻不再对委员会的提议&不买帐&的时候，这样的革新才可能产生。1。…only if…只有在…。的时候才…。。引导条件状语从语。

If you are unfortunate enough to the lovelorn, please tell me, I will help you out, really, please contact me!

如果你不幸失恋了，请告诉我，我会帮助你摆脱困境，真的，请联系我啦！

China's plan to cut energy intensity by 20 percent and pollutant discharges by 10 percent between 2006 and 2010 is a case in point.

中国计划在2006年到2010间降低20%的能源强度和减少10%的主要污染物排放，就是一个这样的例子。