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In this paper: Unsupervised Machine Translation Using Monolingual Corpora Only the authors proposed a novel method. Intuitively it is an autoencoder, but the Start Of Sentence token is set to be the language type. One other advanced method is to use the pre-training model. In this paper: Cross-lingual Language Model Pretraining researchers proposed an ...


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This is called "clustering" , If the network is already trained with data that has similar features as of the "symbols", you can use that network with its last classification layer removed , then run a clustering algorithm like "k-means" on top of the vectors obtained from the last layer of the network.


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