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→Differential equations and mathematical physics
庞加莱为引力旋转流体的平衡图写了重要的天文学著作。他引入了<font color="#ff8000"> 分支点</font>的重要概念，证明了非椭球体（包括环形和梨形）等平衡图形的存在性及其稳定性。这项天文发现奖（1900年）被英国皇家天文学会授予。<ref>A. Kozenko, The theory of planetary figures, pages = 25–26{{full citation needed|date=September 2019}}</ref>
庞加莱为引力旋转流体的平衡图写了重要的天文学著作。他引入了<font color="#ff8000"> 分支点</font>的重要概念，证明了非椭球体（包括环形和梨形）等平衡图形的存在性及其稳定性。这项天文发现奖（1900年）被英国皇家天文学会授予。<ref>A. Kozenko, The theory of planetary figures, pages = 25–26{{full citation needed|date=September 2019}}</ref>
===Differential equations and mathematical physics===
===Differential equations and mathematical physics微分方程与数学物理===
Poincaré's mental organisation was not only interesting to Poincaré himself but also to Édouard Toulouse, a psychologist of the Psychology Laboratory of the School of Higher Studies in Paris. Toulouse wrote a book entitled Henri Poincaré (1910). In it, he discussed Poincaré's regular schedule:
Poincaré's mental organisation was not only interesting to Poincaré himself but also to Édouard Toulouse, a psychologist of the Psychology Laboratory of the School of Higher Studies in Paris. Toulouse wrote a book entitled Henri Poincaré (1910). In it, he discussed Poincaré's regular schedule:
After defending his doctoral thesis on the study of singular points of the system of differential equations, Poincaré wrote a series of memoirs under the title "On curves defined by differential equations" (1881–1882).<ref>French: "Mémoire sur les courbes définies par une équation différentielle"</ref> In these articles, he built a new branch of mathematics, called "[[qualitative theory of differential equations]]". Poincaré showed that even if the differential equation can not be solved in terms of known functions, yet from the very form of the equation, a wealth of information about the properties and behavior of the solutions can be found. In particular, Poincaré investigated the nature of the trajectories of the integral curves in the plane, gave a classification of singular points (saddle, focus, center, node), introduced the concept of a limit cycle and the loop index, and showed that the number of limit cycles is always finite, except for some special cases. Poincaré also developed a general theory of integral invariants and solutions of the variational equations. For the finite-difference equations, he created a new direction – the asymptotic analysis of the solutions. He applied all these achievements to study practical problems of [[mathematical physics]] and [[celestial mechanics]], and the methods used were the basis of its topological works.<ref>{{cite book|editor1-last=Kolmogorov|editor1-first = A.N.|editor2-first = A.P.|editor2-last= Yushkevich|title = Mathematics of the 19th century |volume= 3| pages = 162–174, 283|isbn= 978-3764358457|date = 24 March 1998}}</ref>
After defending his doctoral thesis on the study of singular points of the system of differential equations, Poincaré wrote a series of memoirs under the title "On curves defined by differential equations" (1881–1882).<ref>French: "Mémoire sur les courbes définies par une équation différentielle"</ref> In these articles, he built a new branch of mathematics, called "[[qualitative theory of differential equations]]". Poincaré showed that even if the differential equation can not be solved in terms of known functions, yet from the very form of the equation, a wealth of information about the properties and behavior of the solutions can be found. In particular, Poincaré investigated the nature of the trajectories of the integral curves in the plane, gave a classification of singular points (saddle, focus, center, node), introduced the concept of a limit cycle and the loop index, and showed that the number of limit cycles is always finite, except for some special cases. Poincaré also developed a general theory of integral invariants and solutions of the variational equations. For the finite-difference equations, he created a new direction – the asymptotic analysis of the solutions. He applied all these achievements to study practical problems of [[mathematical physics]] and [[celestial mechanics]], and the methods used were the basis of its topological works.<ref>{{cite book|editor1-last=Kolmogorov|editor1-first = A.N.|editor2-first = A.P.|editor2-last= Yushkevich|title = Mathematics of the 19th century |volume= 3| pages = 162–174, 283|isbn= 978-3764358457|date = 24 March 1998}}</ref>
在为他关于微分方程组奇点研究的博士论文辩护后，庞加莱以“微分方程定义的曲线”（1881-1882）为题写了一系列回忆录。<ref>French: "Mémoire sur les courbes définies par une équation différentielle"</ref>在这些文章中，他建立了一个新的数学分支，叫做“[[微分方程定性理论]]”。Poincaré表明，即使微分方程不能用已知函数来求解，但是从方程的形式来看，可以找到关于解的性质和行为的丰富信息。特别地，Poincaré研究了积分曲线在平面上的轨迹性质，给出了奇异点（鞍点、焦点、中心、节点）的分类，引入了极限环和环指数的概念，证明了除某些特殊情况外，极限环的个数始终是有限的。庞加莱还发展了积分不变量和变分方程解的一般理论。对于有限差分方程，他开创了一个新的方向——解的渐近分析。他将这些成果应用于研究[[数学物理]]和[[天体力学]]的实际问题，所采用的方法是其拓扑学工作的基础。<ref>{{cite book|editor1-last=Kolmogorov|editor1-first = A.N.|editor2-first = A.P.|editor2-last= Yushkevich|title = Mathematics of the 19th century |volume= 3| pages = 162–174, 283|isbn= 978-3764358457|date = 24 March 1998}}</ref>
<gallery caption="The singular points of the integral curves">
<gallery caption="The singular points of the integral curves">
</gallery>
</gallery>
==Character==
==Character==