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

{:B e:boolean e:T} => {:A e:boolean ?Y}.
{:C e:boolean e:T. :B e:boolean e:T} => {:A e:boolean ?Y}.