In this paper, we mainly discuss the class of charming spaces. First, we show that there exists a charming space such that the Tychonoff product is not a charming space. Then we discuss some properties of charming spa...In this paper, we mainly discuss the class of charming spaces. First, we show that there exists a charming space such that the Tychonoff product is not a charming space. Then we discuss some properties of charming spaces and give some characterizations of some class of charming spaces. Finally, we show that the Suslin number of an arbitrary charming rectifiable space is countable.展开更多
Lindelf's equation is derived by using the Vakonomic model,which shows that Lindelf's work coincides with Vakonomic model. Chaplygin's equation is derived by using Chetaev's model, which shows that Cha...Lindelf's equation is derived by using the Vakonomic model,which shows that Lindelf's work coincides with Vakonomic model. Chaplygin's equation is derived by using Chetaev's model, which shows that Chaplygin's work coincides with Chetaev's model. On basis of these, by improving the expressions of Chaplygin's equation and Lindelf's equation, the reasonable transition from Chaplygin's equation to Lindelf's equation is realized, the reasonable transition from Lindelf's equation to Chaplygin's equation is realized too. Finally, a typical example is given. The work of this paper shows that, just as the Vakonomic model and Chetaev's model are complementary to each other, Lindelf's work and Chaplygin's work are complementary to each other too.展开更多
In this paper,we give an example of a Hausdorff centered-Lindelf space X such that St-l(X)=c^+,which negatively answers two questions rasied by Bonanzinga and Matveev.
基金The NSF(11571158,11471153 and 11201414) of Chinathe NSF(2017J01405,2016J05014,2016J01671 and 2016J01672) of Fujian Province of China
文摘In this paper, we mainly discuss the class of charming spaces. First, we show that there exists a charming space such that the Tychonoff product is not a charming space. Then we discuss some properties of charming spaces and give some characterizations of some class of charming spaces. Finally, we show that the Suslin number of an arbitrary charming rectifiable space is countable.
文摘Lindelf's equation is derived by using the Vakonomic model,which shows that Lindelf's work coincides with Vakonomic model. Chaplygin's equation is derived by using Chetaev's model, which shows that Chaplygin's work coincides with Chetaev's model. On basis of these, by improving the expressions of Chaplygin's equation and Lindelf's equation, the reasonable transition from Chaplygin's equation to Lindelf's equation is realized, the reasonable transition from Lindelf's equation to Chaplygin's equation is realized too. Finally, a typical example is given. The work of this paper shows that, just as the Vakonomic model and Chetaev's model are complementary to each other, Lindelf's work and Chaplygin's work are complementary to each other too.
文摘In this paper,we give an example of a Hausdorff centered-Lindelf space X such that St-l(X)=c^+,which negatively answers two questions rasied by Bonanzinga and Matveev.
