我正在使用随机梯度下降通过反向传播来训练一个XOR神经网络。神经网络的权重被初始化为介于-0.5和0.5之间的随机值。神经网络成功地训练了大约80%的时间。然而有时它会在反向传播时“卡住”。所谓的“卡住”,是指我开始看到错误校正速率的下降。例如,在一次成功的训练期间,随着网络学习,总误差会迅速减少:
...
...
Total error for this training set: 0.0010008071327708653
Total error for this training set: 0.001000750550254843
Total error for this training set: 0.001000693973929822
Total error for this training set: 0.0010006374037948094
Total error for this training set: 0.0010005808398488103
Total error for this training set: 0.0010005242820908169
Total error for this training set: 0.0010004677305198344
Total error for this training set: 0.0010004111851348654
Total error for this training set: 0.0010003546459349181
Total error for this training set: 0.0010002981129189812
Total error for this training set: 0.0010002415860860656
Total error for this training set: 0.0010001850654351723
Total error for this training set: 0.001000128550965301
Total error for this training set: 0.0010000720426754587
Total error for this training set: 0.0010000155405646494
Total error for this training set: 9.99959044631871E-4
Testing trained XOR neural network
0 XOR 0: 0.023956746649767453
0 XOR 1: 0.9736079194769579
1 XOR 0: 0.9735670067093437
1 XOR 1: 0.045068688874314006
然而,当它卡住时,总错误数在减少,但似乎是以递减的速率减少:
...
...
Total error for this training set: 0.12325486644721295
Total error for this training set: 0.12325486642503929
Total error for this training set: 0.12325486640286581
Total error for this training set: 0.12325486638069229
Total error for this training set: 0.12325486635851894
Total error for this training set: 0.12325486633634561
Total error for this training set: 0.1232548663141723
Total error for this training set: 0.12325486629199914
Total error for this training set: 0.12325486626982587
Total error for this training set: 0.1232548662476525
Total error for this training set: 0.12325486622547954
Total error for this training set: 0.12325486620330656
Total error for this training set: 0.12325486618113349
Total error for this training set: 0.12325486615896045
Total error for this training set: 0.12325486613678775
Total error for this training set: 0.12325486611461482
Total error for this training set: 0.1232548660924418
Total error for this training set: 0.12325486607026936
Total error for this training set: 0.12325486604809655
Total error for this training set: 0.12325486602592373
Total error for this training set: 0.12325486600375107
Total error for this training set: 0.12325486598157878
Total error for this training set: 0.12325486595940628
Total error for this training set: 0.1232548659372337
Total error for this training set: 0.12325486591506139
Total error for this training set: 0.12325486589288918
Total error for this training set: 0.12325486587071677
Total error for this training set: 0.12325486584854453
在我阅读神经网络的相关资料时,我看到了有关局部最小值和全局最小值的讨论。神经网络并不真正“知道”它应该向哪个最小值前进。
我的神经网络是否陷入了局部最小值而不是全局最小值?