Concatenation (CONC) is used as the first step for ensembling multiple vectors of different dimensions.
let S be a set of n semantic spaces and s i be a single vector space in S. e id ∈ s i is a representation of word w d in the semantic space s i ∈ S. Then the resulting concatenated embedding e d of word w d is where ⊕ is the concatenation operator and i α i = 1.