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courses:rg:2012:longdtreport [2012/03/12 22:47] longdt |
courses:rg:2012:longdtreport [2012/03/12 22:59] (current) longdt |
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| __Sorted Array__ | __Sorted Array__ | ||
| - | + Use n array for n-gram model (array i-th is used for i-gram) | + | |
| - | | + | - Use n array for n-gram model (array i-th is used for i-gram) |
| - | | + | - Each element in array in pair (w,c) |
| - | | + | |
| - | | + | |
| + | - Sort base on w | ||
| Improvement : Implicitly encode W (all n-gram ending with particular word wi are stored -> wasteful. So, maintain another array save the beginning and the end of the range | Improvement : Implicitly encode W (all n-gram ending with particular word wi are stored -> wasteful. So, maintain another array save the beginning and the end of the range | ||
| Line 38: | Line 40: | ||
| __Variable length coding__ | __Variable length coding__ | ||
| - | | ||
| - | Most of the attendants apparently understood the talk and the paper well, and a | ||
| - | lively discussion followed. One of our first topics of debate was the notion of | ||
| - | skyline presented in the paper. The skyline was somewhat of a supervised element | ||
| - | -- the authors estimated initial parameters for a model from gold data and | ||
| - | trained it afterwards. They assumed that a model with parameters estimated from | ||
| - | gold data cannot be beaten by an unsupervisedly trained model. Verily, after | ||
| - | training the skyline model, its accuracy dropped very significantly. The reasons | ||
| - | of this were a point of surprise for us as well as for the paper' | ||
| - | Complementary | + | Idea : |
| - | definitely be beaten by their final model. This baseline, they called | + | Context offset tend to be close with each others, => Only save the first offsets address and the difference of others with the it |
| - | " | + | |
| - | used in this model. We could only speculate | + | |
| - | probability distribution. | + | |
| - | A point about unsupervised language modeling came out: Many linguistic phenomena | + | Question |
| - | are annotated in a way that is to some extent arbitrary, and reflects more the | + | how the unigram be sorted ? |
| - | linguistic theory used than the language itself, and an unsupervised model | + | Martin suggest that it must be sorted base on frequency |
| - | cannot hope to get them right. The example we discussed was whether the word | + | |
| - | " | + | |
| - | noticed that dependency orientation in general was not a particularly strong | + | |
| - | point of their parser, and so they also included an evaluation metric that | + | |
| - | ignored the dependency orientations. | + | |
| - | Perhaps the most crucial observations the authors made was that there is a limit | + | __Block Compression__ |
| - | where feeding more data to the model training hurts its accuracy. They | + | compress |
| - | progressed from short sentences to longer, and identified | + | the underline reason is only to support binary search |
| - | it's best to start ignoring any more training data, at sentences | + | |
| - | However, we were not 100% clear how they computed this constant. | + | |
| - | If the model was to be fully unsupervised, | + | |
| - | this threshold, because it cannot be safely assumed that it would be the same | + | |
| - | for all languages and setups. | + | |
| - | The writing style of the paper was also a matter of differing opinions. | + | ==== Decoding ==== |
| - | Undeniably, it is written in a vocabulary-intensive fashion, bringing readers | + | **I. Exploiting Repetitive Queries** |
| - | face to face with words like " | + | |
| - | never seen before. | + | |
| - | ==== Conclusion ==== | + | The method use cache to speed up the process |
| + | This simple implementation increase performance of 300% over conventional implementation | ||
| + | **II. Exploiting Scrolling Queries** | ||
| - | All in all, it was a paper worth reading, well presented, and thoroughly | + | We can quickly form the context encoding of the next query by concatenating new words with saved offset from previous query |
| - | discussed, bringing useful general ideas as well as interesting details. | + | |
| + | ==== Conclusion ==== | ||
| + | In summary, it was a worth reading | ||
| + | discussed. | ||
