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But only in the last decade have researchers begun to measure happiness across the life span and, in doing so, try to understand why older people tend 阅读全文
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https://baike.baidu.com/item/格拉姆矩阵/16274086 https://en.wikipedia.org/wiki/Gramian_matrix https://en.wikipedia.org/wiki/Matrix_congruence https://en.wi 阅读全文
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小结： 1、同余关系或简称同余是相容于某个代数运算的等价关系。 https://baike.baidu.com/item/同余关系 https://en.wikipedia.org/wiki/Congruence_relation https://en.wikipedia.org/wiki/Equi 阅读全文
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https://baike.baidu.com/item/同态 假设M，M′是两个乘集，也就是说M和M′是两个各具有一个封闭的具有结合律的运算*与*‘的代数系统。σ是M射到M′的映射，并且任意两个元的乘积的像是这两个元的像的乘积，即对于M中任意两个元a、b，满足σ(a*b)=σ(a)*’σ(b)；也 阅读全文
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https://en.wikipedia.org/wiki/Congruence_relation In abstract algebra, a congruence relation (or simply congruence) is an equivalence relation on an a 阅读全文
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1、透明 https://en.wikipedia.org/wiki/Equivalence_relation In mathematics, an equivalence relation is a binary relation that is reflexive, symmetric and 阅读全文
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小结： 1、 销量 广告 微分方程 动态系统 市场份额 https://en.wikipedia.org/wiki/Sethi_model The Sethi model was developed by Suresh P. Sethi and describes the process of ho 阅读全文
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小结： 1、非奇异的；非退化的：只有输入为0（可以泛化的概念）结果才为0 2、If A ∈ Mm,n(F) and m < n, then A isnecessarily singular. A s*n s<n 则A必然奇异的。 A linear transformation or matrix i 阅读全文