Static embeddings
Static embeddings are the oldest type of word embedding. The embeddings are generated against a large corpus but the number of words, though large, is finite. You can think of a static embedding as a dictionary, with words as the keys and their corresponding vector as the value. If you have a word whose embedding needs to be looked up that was not in the original corpus, then you are out of luck. In addition, a word has the same embedding regardless of how it is used, so static embeddings cannot address the problem of polysemy, that is, words with multiple meanings. We will explore this issue further when we cover non-static embeddings later in this chapter.
Word2Vec
The models known as Word2Vec were first created in 2013 by a team of researchers at Google led by Tomas Mikolov [1, 2, 3]. The models are self-supervised, that is, they are supervised models that depend on the structure of natural language to provide labeled training data.
The two architectures...
