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Discussion 1
Should we allow free
variables in lfp, ifp, pfp ?
•Example
•Colored
graph: E(x, c, y)
•Check
if every pair of nodes is connected by a path where all edges have the same
color:
8 x.8 y.9 c.[lfpR,x,yf(R,
x,y,c)](x,y)
Where
f(R,x,y,c)
= E(x,c,y) Ç 9 z.(R(x,z) Æ E(z,c,y))