Assertion: graph's vertex | /r/HasProperty | coloured
Facets:
value: by using just four colours
type: MANNER
value: always
type: TEMPORAL
Source sentences:
text: In an equivalent graph-theoretic form, one may translate this problem to ask whether the vertices of a planar graph can always be coloured by using just four colours in such a way that vertices joined by an edge have different colours.
text: An order-4 Venn diagram, which can be interpreted as a subdivision drawing of a hypergraph with 15 vertices (the 15 colored regions) and 4 hyperedges (the 4 ellipses).