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Discussion 2
•Simultaneous fixpoints
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•Is there a path of even length from a to b ?
[lfpR,xf(R, S, x),y(R, S, x)](b)
Where
 f(R,S,x) = 9 z.(S(x,z) Æ E(z,x))
y(R,S,x) = E(a,x) Ç 9 z.(R(x,z) Æ E(z,x))
EXPRESS THE SAME THING WITH ONLY ONE LFP !