@prefix e: <http://eulersharp.sourceforge.net/2003/03swap/log-rules#>.
@prefix : <http://eulersharp.sourceforge.net/2007/07test#>.

### snow is not black and things are black or white

{:snow :hasColor :black} e:boolean e:F.

{{?S :hasColor :black} e:boolean e:T} => {{?S :hasColor :white} e:boolean e:F}.
{{?S :hasColor :white} e:boolean e:T} => {{?S :hasColor :black} e:boolean e:F}.