**Go backward to **Solution to part (a)

**Go up to **3 Proofs and Logical Consequences (ground)

**Go forward to **Solution to part (c)

## Solution to part (b)

"*a* isn't a logical consequence of *KB*" means there exists a model of
*KB* in which *a* is false.
To show why *a* isn't a logical consequence of *KB*, we can give such
a model. The minimal model will always be one such model.
This model has *{h,e,d,c,g}* all true and *{a,b,f}* all false.

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material, ©David Poole, Alan Mackworth and Randy Goebel, 1998