892.txt

This complete matlab for neural network

发信人: waterflower (农民上访工人下岗某些分子搞三讲), 信区: DataMining
标  题: Re: 再问
发信站: 南京大学小百合站 (Sun Mar 10 00:37:37 2002), 站内信件

【 在 xlcy (all nothing) 的大作中提到: 】
: 首先谢谢joe的回答，你的回答由一定的道理
: 不过对于第二个问题我认为最根本的原因不是这样的，
: 我用了一个下午的时间琢磨了一番
: 把P231上join step看了好几遍，基本上明白了
: 应该是这样吧：
: to find Lk,we should use achive Ck first by joining Lk-1.
: when joining Lk-1∞Lk-1,we should ensure their members's first (k-2) items 
: are equivalent. then we just combine the last one item to get new itemset 
: for Ck.
: for example:
: C3=L2∞L2={{I1,I2},{I1,I3},{I1,I5},{I2,I3},{I2,I4},{I2,I5}}∞{{I1,I2},
:            {I1,I3},{I1,I5},{I2,I3},{I2,I4},{I2,I5}}
: to get C3, k-2=1. so we should ensure the first item of itemset, which will
: have join action, are equivalent. here, just the first three itemset and the
: last three ones satisfy this condition. So start form{I1,I2},{I1,I3},{I1,I5}
: we can get part of C3 {I1,I2,I3},{I1,I2,I5},{I1,I3,I5}(keep the k-2 item cons
: tant and 
: combine the last item,I2,I3,I5). the same to {I2,I3,I4},{I2,I3,I5},{I2,I4,I5}.
: so the number of itemsets in C3 is 6.
agree with you!!you can get the slides from Dr. Zhou's
homepage for deep comprehension.
: what's more, the next step is prune step,which is used to get L3 according to
: (以下引言省略 ... ...)

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