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annotate writeup/aistats_review_response.txt @ 620:5c67f674d724

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more changes to rebuttal
author Yoshua Bengio <bengioy@iro.umontreal.ca>
date Sun, 09 Jan 2011 14:35:03 -0500
parents ea31fee25147
children d44c78c90669
rev   line source
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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1
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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2 We thank the authors for their thoughtful comments. Please find our responses below.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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4 * Comparisons with shallower networks, but using unsupervised pre-training:
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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5 e will add those results to the paper. Previous work in our group with
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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6 very similar data (the InfiniteMNIST dataset were published in JMLR in 2010
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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7 "Why Does Unsupervised Pre-training Help Deep Learning?"). The results indeed
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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8 show improvement when going from 1 to 2 and then 3 layers, even when using
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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9 unsupervised pre-training (RBM or Denoising Auto-Encoder).
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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11 * Comparisons with SVMs. We have tried several kinds of SVMs. The main limitation
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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12 of course is the size of the training set. One option is to use a non-linear SVM
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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13 with a reduced training set, and the other is to use an online linear SVM.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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14 Another option we have considered is to project the input non-linearly in a
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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15 high-dimensional but sparse representation and then use an online linear SVM on that space.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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16 For this experiment we have thresholded input pixel gray levels considered a
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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17 low-order polynomial expansion (e.g. only looking at pairs of non-zero pixels).
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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18 We have obtained the following results until now, all substantially worse than those
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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19 obtained with the MLP and deep nets.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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20
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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21 SVM type training set input online validation test set
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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22 type / size features training set error error
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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23 error
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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24 Linear SVM, NIST, 651k, original, 36.62%, 34.41%, 42.26%
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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25 Linear SVM, NIST, 651k, sparse quadratic, 30.96%, 28.00%, 41.28%
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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26 Linear SVM, NISTP, 800k, original, 88.50%, 85.24%, 87.36%
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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27 Linear SVM, NISTP, 800k, sparse quadratic, 81.76%, 83.69%, 85.56%
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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28 RBF SVM, NISTP, 100k, original, 74.73%, 56.57%, 64.22%
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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29
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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30 The best results were obtained with the sparse quadratic input features, and
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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31 training on the CLEAN data (NIST) rather than the perturbed data (NISTP).
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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33
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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34 * Using distorted characters as the corruption process of the Denoising
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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35 Auto-Encoder (DAE). We had already performed preliminary experiments with this idea
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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36 and it did not work very well (in fact it depends on the kind of distortion
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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37 considered), i.e., it did not improve on the simpler forms of noise we used
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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38 for the AISTATS submission. We have several interpretations for this, which should
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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39 probably go (along with more extensive simulations) into another paper.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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40 The main interpretation for those results is that the DAE learns good
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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41 features by being given as target (to reconstruct) a pattern of higher
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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42 density (according to the unknown, underlying generating distribution) than
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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43 the network input. This is how it gets to know where the density should
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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44 concentrate. Hence distortions that are *plausible* in the input distribution
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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45 (such as translation, rotation, scaling, etc.) are not very useful, whereas
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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46 corruption due to a form of noise are useful. In fact, the most useful
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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47 is a very simple form of noise, that guarantees that the input is much
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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48 less likely than the target, such as Gaussian noise. Another way to think
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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49 about it is to consider the symmetries involved. A corruption process should
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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50 be such that swapping input for target should be very unlikely: this is
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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51 true for many kinds of noises, but not for geometric transformations
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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52 and deformations.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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53
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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54 * Human labeling: We controlled noise in the labelling process by (1)
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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55 requiring AMT workers with a higher than normal average of accepted
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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56 responses (>95%) on other tasks (2) discarding responses that were not
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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57 complete (10 predictions) (3) discarding responses for which for which the
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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58 time to predict was smaller than 3 seconds for NIST (the mean response time
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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59 was 20 seconds) and 6 seconds seconds for NISTP (average response time of
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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60 45 seconds) (4) discarding responses which were obviously wrong (10
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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61 identical ones, or "12345..."). Overall, after such filtering, we kept
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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62 approximately 95% of the AMT workers' responses. We thank the reviewer for
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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63 the suggestion about multi-stage questionnaires, we will definitely
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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64 consider this as an option next time we perform this experiment. However,
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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65 to be fair, if we were to do so, we should also consider the same
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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66 multi-stage decision process for the machine learning algorithms as well.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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67
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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68 * Size of labeled set: in our JMLR 2010 paper on deep learning (cited
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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69 above), we already verified the effect of number of labeled examples on the
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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70 deep learners and shallow learners (with or without unsupervised
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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71 pre-training); see fig. 11 of that paper, which involves data very similar
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Yoshua Bengio <bengioy@iro.umontreal.ca>
parents: 619
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72 to those studied here. Basically (and somewhat surprisingly) the deep
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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73 learners with unsupervised pre-training can take more advantage of a large
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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74 amount of labeled examples, presumably because of the initialization effect
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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75 (that benefits from the prior that representations that are useful for P(X)
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Yoshua Bengio <bengioy@iro.umontreal.ca>
parents: 619
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76 are also useful for P(Y|X)), and the effect does not disappear when the
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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77 number of labeled examples increases. Other work in the semi-supervised
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Yoshua Bengio <bengioy@iro.umontreal.ca>
parents: 619
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78 setting (Lee et al, NIPS2009, "Unsupervised feature learning...") also show
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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79 that the advantage of unsupervised feature learning by a deep architecture
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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80 is most pronounced in the semi-supervised setting with very few labeled
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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81 examples. Adding the training curve in the self-taught settings of this AISTAT
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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82 submission is a good idea, but probably unlikely to provide results
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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83 different from the above already reported in the literature in similar
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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84 settings.
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Yoshua Bengio <bengioy@iro.umontreal.ca>
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85