BDD: ws17 exercise 5 mistake + apply algorithm

Question

Hello,

I don't know if this has been mentioned before, but in ws17 ex. 5a) the truth table is wrong for x,y,z=0. According to my calculations, f should be 0. Will the BDD change and how?
Also, another question referring 5c): Why do we connect the c node with the d node when c=1 and not vice versa?

Comments

I don't find a mistake in that exam paper, can you double-check which exam paper and exercise it is, and maybe you can edit your question and add the function we talk about to make sure that we do not look at different problems.

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I think I calculated the implication before the XOR operation.I didn't know the priority order I guess.

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The precedences are as follows:
LOWEST
    1. EQV
    2. IMP
    3. OR
    4. XOR
    5. AND
    6. NEG
    HIGHEST

Answer 1

So, I guess the first question is already answered if it was a wrong use of the operator precedences: XOR binds stronger than implication. If you have doubts about something like this, please ask in exams.

For problem 5c, one should compute the conjunction of BDDs for ((a∧¬b)∨c) and a∧b∧¬d ∨ ¬a which should produce the following BDDs:

  &  =   

Note that the ordering is given and therefore c must occur before d on the paths.