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    Multicolour Erdős--Hajnal Conjecture
Conjecture   For every fixed  and fixed colouring
 and fixed colouring  of
 of  with
 with  colours, there exists
 colours, there exists  such that every colouring of the edges of
 such that every colouring of the edges of  contains either
 contains either  vertices whose edges are coloured according to
 vertices whose edges are coloured according to  or
 or  vertices whose edges are coloured with at most
 vertices whose edges are coloured with at most  colours.
 colours. 
 and fixed colouring
 and fixed colouring  of
 of  with
 with  colours, there exists
 colours, there exists  such that every colouring of the edges of
 such that every colouring of the edges of  contains either
 contains either  vertices whose edges are coloured according to
 vertices whose edges are coloured according to  or
 or  vertices whose edges are coloured with at most
 vertices whose edges are coloured with at most  colours.
 colours. See [FGP].
Bibliography
[FGP] Jacob Fox, Andrey Grinshpun and János Pach: The Erdős–Hajnal conjecture for rainbow triangles, J. Combin. Theory, Series B. 111 (2016), 75--125.
* indicates original appearance(s) of problem.
 
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