Gradient boosting regression is a technique that learns from its mistakes. Essentially, it tries to fit a bunch of weak learners. There are two things to note:
一个数的序列ai,当a1 < a2 < … < aS的时候,我们称这个序列是上升的。对于给定的一个序列(a1, a2, …, aN),我们可以得到一些上升的子序列(ai1, ai2, …, aiK),这里1 <= i1 <i2 < … < iK <= N。比如,对于序列(1, 7, 3, 5,...