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+1 vote

Hello everybody,

in order to check whether my solutions are right I would like to use the vrs online tool for getting Shannon Normal Form, however I can not really see how to read them. As example I have the given formula a & (a->b) from the lecture. With transforming we get (a => (b=>1|0) | 0). And I see that.

The online tool gives me

(b ? (a ? true
            : false)
       : false)

and I additionally have the Shannon graph showing up. Would some one mind helping me out with this?

in * TF "Emb. Sys. and Rob." by (650 points)

1 Answer

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Best answer
Well, it is just another syntax which is the one typically used in programming languages. Your example is (b => (a => 1|0) | 0).

The Shannon graph is not that useful for generating the SNF, since it is just a BDD which is neither ordered nor reduced. However, you may use the BDD instead (best let the tool print both leaf nodes).
by (166k points)
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For my understandings, we just switch the order of the variables but maintain of course the semantics. With this we can read this like a BDD but from the bottom up, in terms of variable? With the example formula, starting now in with b and then a?
Well. b is outside in this SNF, a is inside. So b has the higher variable ordering. If we draw a BDD, we draw it top to bottom while reading the SNF from the outside.

You can change the variable ordering. Then you'd start with a. (a => … | 0) Then you'd continue for the remaining formula (1 & (1->b)) and variable b. This would yield (a => (b => 1|0) | 0).
Thank you very much for clarifying this.
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