Sentence:  <WSD>Quasiregular</WSD> maps are a generalization of quasiconformal maps where the assumption of injectivity is relaxed. Heinonen and Holopainen [138] developed nonlinear potential theory and <WSD>quasiregular</WSD> maps on Carnot groups. 
Meaning of the word marked with <WSD> tags:  Having certain properties in common with holomorphic functions of a single complex variable.