Update relatedwork.tex

AAAI2021/tex/relatedwork.tex

@@ -4,10 +4,11 @@
 %external environmental factors
 Previous works focus on the external environmental factors that impact the
 compositionality of emerged symbolic language. 
-For example, XXX proposed small vocabulary sizes~\cite{}.
-XXX proposed memoryless~\cite{}.
-XXX proposed carefully constructed distractors~\cite{}.
-XXX proposed ease-of-teaching~\cite{}.
+For example, ~\citet{kirby2015compression} explored how the pressures for compressivity and compressibility lead the structured language.
+~\citet{kottur-etal-2017-natural} constrained the vocabulary size and whether the listener has memory to coax the compositionality of the emergent language.
+~\citet{lazaridou2018emergence} showed that the degree of structure found in the input data affects the emergence of the symbolic language.
+~\citet{li2019ease} studied how the pressure, ease of teaching, impact on the iterative language of the population regime.
+~\citet{evtimova2018emergent} designed a novel multi-modal scenarios, which the speaker and the listener should access to different modalities of the input object, to explore the language emergence.
 Such factors are deliberately designed, which are too ideal to be true in
 the real world. None of these works realizes the importance of model capacity of
 agent itself. \rmk{this should be largely emphasized.}