Question You are just starting a quiet evening at home when an old friend calls

Question

Question

You are just starting a quiet evening at home when an old friend calls to announce he is coming over for   dinner at your place. This being a big surprise, you immediately undertake emergency dinner preparations.

Within a few minutes, you have managed to load up the BARTENDER expert system on your PC so that you can select a drink.BARTENDER is a backwardchaining production system with rules given below. Note that when more than one rule has a consequent matching the current problem, those rules are tried in the order given in the list.

Rule 1:    IF     expensive wine is selected

                AND    it is 31st of December

                THEN   champagne

Rule 2:    IF     expensive wine is selected   

                AND    first meal is steak

                THEN   red wine

Rule 3:    IF     cheap wine is selected

                AND    first meal is chicken

                AND    guest is not wellliked

                THEN   apple wine

Rule 4:    IF     cheap wine is selected

                AND    first meal is unknown

                THEN   pink wine

Rule 5:    IF     beer is selected

                AND    first meal is Mexican beans

                THEN   Spanish beer

Rule 6:    IF     beer is selected

                THEN   Tuborg

Rule 7:    IF     guest is concerned about his health

                THEN   Efes

Rule 8:    IF     guest is concerned about his health

                AND    carrots are not to be served

                THEN   carrot juice

Rule 9:    IF     wine is selected

                AND    guest should be impressed

                THEN   expensive wine

Rule 10: IF     wine is selected

                THEN   cheap wine

Rule 11: IF     guest is sophisticated

                THEN   wine

Rule 12: IF     first meal is Mexican beans

                THEN   beer

Rule 13: IF     guest is not wellliked

                AND    first meal is provided by Restaurant X

                THEN   beer

Rule 14: IF     true

                THEN   water

BARTENDER's hypotheses are as follows:

     champagne

     red wine

     pink wine

      apple wine

     Spanish beer

     Tuborg

     Efes

     carrot juice

- water

Now here are some facts to assume true, if an inquiry is made:

first meal is provided by Restaurant X

     first meal is Mexican beans

     guest is not wellliked

     guest is sophisticated

     it is 31st of December

     first meal is chicken

And here are some facts to assume false, if an inquiry is made:

carrots are not to be served

     first meal is unknown

     guest is concerned about his health  

     guest should be impressed

     first meal is steak

  Note that:

1. In working this problem, remember that the BARTENDER program has no means for problem solving except using the rules.

2. Assume that a user answers questions using BARTENDER's hypotheses given above.

3. Assume BARTENDER's control structure is such that it never asks the user if an assertion is true if there is any rule with that assertion in its THEN part. If there are such rules, but none verifies the assertion, the assertion is assumed to, be false.

4. Assume BARTENDER stops when one hypothesis is verified.

  PART A

Simulate BARTENDER's behaviour on the given facts. Take care to use the hypotheses in the given order. Indicate your answer by showing the sequence in which the rules fire and the name of the drink selected.

Rule Number                     Selected Drink

PART B

With some different set of facts, could BARTENDER ever recommend the red wine with Mexican beans? If not, why not?

SOLUTION:

PART C

With some different set of facts, could BARTENDER ever recommend carrot juice with steak? If not, why not?

SOLUTION:

PART D

Assume the existing rule set is added with a collection of meta rules. Each metarule is to be tried, possibly initiating some backwardchaining, before the ordinary process of hypothesis checking and backwardchaining begins. Here are the metarules:

M1:      IF   the first meal is chicken

            THEN delete rules 12 and 13

M2:      IF   expensive wine is selected

            THEN delete rules 2 and 4

            AND replace rule 3 with rule 15 (below)

Rule 15:IF   cheap wine is selected

              THEN Villa Doluca

Now determine which drink will be selected again given the set of facts to be assumed true. You need only to specify the drink; do not bother to show the order the rules are used.

Explanation / Answer

PART A:.

BARTENDER's behaviour on the given facts are

as my knowledge Bartender will select the Rule1 and drink is Compagne

because of the December 31st

PART B:

BARTENDER doesn't recommend the red wine with Mexican beans.because

Rule 2:    IF     expensive wine is selected   

                AND    first meal is steak

                THEN   red wine

in this above case expensive wine is selected first meal is Steak then only red whine,

there is no Mexican bean as per rule 2.

PART C:

Bartender couldn;t recommend carrot juice with Steak.because

Rule 8:    IF     guest is concerned about his health

                AND    carrots are not to be served

                THEN   carrot juice

PART D:

given the set of facts to be assumed true. I need to spicify the drink Pink wine.

so as per condition Rule 15 cheep wine is selected then Villa Doluca

and above conditions some rules may be deleted so thats why i am selected Pink wine.

Because of the above condition guest is concerned his health and carrots are not served then carrot juice.

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