There are a number of concepts in model theory - often situated around Hrushovski's amalgamation method (see for instance <http://math.univ-lyon1.fr/~wagner/nijmegen.pdf>) - which are colorfully named:


* Green fields (e.g. <http://arxiv.org/pdf/1003.5149.pdf>)
* Red fields, or red additive groups of fields (e.g., <http://projecteuclid.org/download/pdf_1/euclid.jsl/1174668392>)
* Green, white, black, and emerald points (e.g., <http://arxiv.org/pdf/1401.0495.pdf>)


My question is, where does this terminology come from? And is there a pattern to it - that is, would it have been as reasonable to call black points "white points" instead, or would that violate some broad convention?



Colorful model theory
These colors were supplied by Poizat as an abbreviation. If there was any rationale for the choice of colors it escaped me.


