<<An Introduction to Systems Biology>> 笔记

CH1
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CH12 
Every time the goal changes, these modules need only be rewired in order to satisfy the new goal. If the goal stops changing for a sufficient length of time, the networks in the simulation begin to lose modularity and evolve toward a nonmodular design, a design that is typically more optimal(e.g. uses fewer components).
这与软件开发和软件优化的思想如出一辄！
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Thus, the ability to reconfigure and adapt to new confitions may be one force that helps to maintain modular structure in biological systems. 
这有点到哲学层面的味道
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simplicity level 1:
the structural simplicity associated with modularity and the small number of network motifs that make up the networks.
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simplicity level 2:
be able to treat regulatory circuits with simplified mathematical models(the dynamics of transcription circuits) that capture the essence of the behavior and have a certain degree of universality.
也就是说：
把the dynamics of transcription circuits)表示为：ODE/PDE
把molecular details(proteins data)表示为：ODE/PDE的系数(或者说是参数)
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Integral feedback can be shown in many cases to be a unique solution to the problem of robust adaptation in the context of engineering control theory.
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modularity,即模块和模块之间相互独立，这类似于数学上的正交分解。
modularity的目的是为了模块可以重复使用：用已有的若干模块的组合去解决新的问题。（模块之间尽可能相互独立）
正交分解的目的是为了找出线性无关的基向量（或基函数），用这些基向量（或基函数）的线性组合去表示问题空间。
modularity和正交分解都可以看作是把复杂问题转化为稍微简单一些的问题