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author Frederic Bastien <nouiz@nouiz.org>
date Fri, 02 Nov 2012 13:02:18 -0400
parents 4a1339682c8f
children
rev   line source
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067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
parents:
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1
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
parents:
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2 YB. I am very worried about this proposal. It looks again like we would be
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
parents:
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3 creating another language to replace one we already have, namely python,
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
parents:
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4 mainly so that we could have introspection and programmable changes
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
parents:
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5 into an existing control flow structure (e.g. the standard DBN code).
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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6
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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7 I feel that the negatives outweigh the advantages.
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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8
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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9 Please correct me:
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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10
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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11 Disadvantages:
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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12
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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13 * much more difficult to read
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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14 * much more difficult to debug
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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16 JB asks: I would like to try and correct you, but I don't know where to begin --
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17 - What do you think is more difficult to read [than what?] and why?
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18 - What do you expect to be more difficult [than what?] to debug?
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067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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21 Advantages:
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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22
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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23 * easier to serialize (can't we serialize an ordinary Python class created by a normal user?)
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
parents:
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24 * possible but not easier to programmatically modify existing learning algorithms
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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25 (why not the usual constructor parameters and hooks,
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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26 when possible, and just create another code for a new DBN variant when it can't fit?)
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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27 * am I missing something?
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
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29 JB replies:
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30 - Re serializibility - I think any system that supports program pausing,
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31 resuming, and dynamic editing (a.k.a. process surgery) will have the flavour
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James Bergstra <bergstrj@iro.umontreal.ca>
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32 of my proposal. If someone has a better idea, he should suggest it.
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33
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34 - Re hooks & constructors - the mechanism I propose is more flexible than hooks and constructor
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35 parameters. Hooks and constructor parameters have their place, and would be
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36 used under my proposal as usual to configure the modules on which the
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James Bergstra <bergstrj@iro.umontreal.ca>
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37 flow-graph operates. But flow-graphs are more flexible. Flow-graphs
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38 (REPEAT, CALL, etc.) that are constructed by library calls can be directly
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James Bergstra <bergstrj@iro.umontreal.ca>
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39 modified. You can add new hooks, for example, or add a print statement
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James Bergstra <bergstrj@iro.umontreal.ca>
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40 between two statements (CALLs) that previously had no hook between them.
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James Bergstra <bergstrj@iro.umontreal.ca>
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41 - the analagous thing using the real python VM would be to dynamically
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42 re-program Python's compiled bytecode, which I don't think is possible.
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067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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44 I am not convinced that any of the stated advantages can't be achieved in more traditional ways.
067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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46 RP comment: James or anybody else correct me if I'm wrong. What I think James
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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47 proposed is just a way encapsulating different steps of the program in some
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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48 classes. These classes are serializable. They are not a programming language
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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49 per se. The way I see it is like dividing your program in a set of functions.
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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50 Each function is a control flow element applied to something ( like a CALL to
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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51 a python function ). The idea is to wrap this functions around something to
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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52 make them serializable, and also offer the added advantage that you have a
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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53 graph that presents the order in which you should call the functions and you
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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54 can play with that order.
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067b2f9ba122 comments by YB on JB's arch_sr/plugin_JB.py
Yoshua Bengio <bengioy@iro.umontreal.ca>
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55
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56 That is why I was trying to convince James to re-write things ( using some
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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57 syntactic sugar) to make it look less intimidating ( I believe it can look
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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58 much more "traditional" that it looks right now). I think a programming
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Razvan Pascanu <r.pascanu@gmail.com>
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59 language might also be a overloaded term that so we might speak about
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Razvan Pascanu <r.pascanu@gmail.com>
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60 different things. But if all that his proposal does is to offer some wrapper
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61 around python function that makes them serializable, and generate a execution
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Razvan Pascanu <r.pascanu@gmail.com>
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62 order graph in which you can possible do simple operations ( like
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63 substitutions and replacements) I would not call it a programming language.
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64
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65 I think the advantage of making the program aware where in its own execution
316410a38f6f comment on Yoshua's comment on James architecture
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66 flow it is and what is its execution flow can be quite useful for automating
316410a38f6f comment on Yoshua's comment on James architecture
Razvan Pascanu <r.pascanu@gmail.com>
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67 some of the things we want.
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Olivier Delalleau <delallea@iro>
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68
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Olivier Delalleau <delallea@iro>
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69 OD comments: I agree with Yoshua. I actually thought (by watching at the
808e38dce8d6 Replied to YB's comment on JB's system
Olivier Delalleau <delallea@iro>
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70 discussions in these files from a rather high-level point-of-view) the main
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Olivier Delalleau <delallea@iro>
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71 goal of this machinery was to help with parallelization. If that is the case,
808e38dce8d6 Replied to YB's comment on JB's system
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72 it may prove useful in some places, but it is not something that one would
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Olivier Delalleau <delallea@iro>
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73 want to use everywhere. As far as serialization is concerned, I think this
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74 should be do-able without such a system (provided we all agree that we do not
808e38dce8d6 Replied to YB's comment on JB's system
Olivier Delalleau <delallea@iro>
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75 necessarily require the ability to serialize / restart at any point). About
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76 the ability to move / substitute things, you could probably achieve the same
808e38dce8d6 Replied to YB's comment on JB's system
Olivier Delalleau <delallea@iro>
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77 goal with proper code factorization / conventions.
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78
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79 JB replies:
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80 You are right that with sufficient discipline on everyone's part,
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81 and a good design using existing python control flow (loops and functions) it is
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82 probably possible to get many of the features I'm claiming with my proposal.
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83
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84 But I don't think Python offers a very helpful syntax or control flow elements
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85 for programming parallel distributed computations through, because the python
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86 interpreter doesn't do that.
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87
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88 What I'm trying to design is a mechanism that can allow us to *express the entire
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89 learning algorithm* in a program. That means
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90 - including the grid-search,
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91 - including the use of the cluster,
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92 - including the pre-processing and post-processing.
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93
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94 To make that actually work, programs need to be more flexible - we need to be
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95 able to pause and resume 'function calls', and to possibly restart them if we
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96 find a problem (without having to restart the whole program). We already do
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97 these things in ad-hoc ways by writing scripts, generating intermediate files,
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98 etc., but I think we would empower ourselves by using a tool that lets us
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99 actually write down the *WHOLE* algorithm, in one place rather than as a README
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100 with a list of scripts and instructions for what to do with them (especially
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101 because the README often never gets written).
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102
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103 OD replies: I can see such a framework being useful for high-level experiment
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104 design (the "big picture", or how to plug different components together). What
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Olivier Delalleau <delallea@iro>
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105 I am not convinced about is that we should also use it to write a standard
ab1db1837e98 JB's plugin: Reply to JB
Olivier Delalleau <delallea@iro>
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106 serial machine learning algorithm (e.g. DBN training with fixed
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Olivier Delalleau <delallea@iro>
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107 hyper-parameters).
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108
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109 RP replies : What do you understand by writing down a DBN. I believe the
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Razvan Pascanu <r.pascanu@gmail.com>
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110 structure and so on ( selecting the optimizers) shouldn't be done using this
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Razvan Pascanu <r.pascanu@gmail.com>
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111 approach. You will start using this syntax to do early stopping, to decide the
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Razvan Pascanu <r.pascanu@gmail.com>
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112 order of pre-training the layers. In my view you get something like
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Razvan Pascanu <r.pascanu@gmail.com>
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113 pretrain_layer1, pretrain_layer2, finetune_one_step and then starting using
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114 James framework. Are you thinking in the same terms ?
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115
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116 OD replies: Actually I wasn't thinking of using it at all inside a DBN's code.
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Olivier Delalleau <delallea@iro>
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117 I forgot early stopping for each layer's training though, and it's true it may
4a1339682c8f Reply to RP
Olivier Delalleau <delallea@iro>
parents: 1251
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118 be useful to take advantage of some generic mechanism there... but I wouldn't
4a1339682c8f Reply to RP
Olivier Delalleau <delallea@iro>
parents: 1251
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119 use James' framework for it.