all the responses so far got me more confused

my intent was not to include "don`t care",thought i could bring it in.as earlier advised,i will have to re-read the question to enable correct my error.

Study the question again and think about what it says before trying to solve the problem.

Think about the logic you used to decide whether the rows you marked as don't cares are really don't cares. If the door is opened and the engine is on and the headlights are on; is that really a don't care? Could two alarm events occurring at the same time disable an alarm?

You drew a truth table. Have you been taught about truth tables, but not Kmaps? It would be helpful for us to know what you've been taught so we can guide you in the right direction. From your first post, I assumed that you had learned about Kmaps.

 

Thanks for contributing, but this is Homework Help. We don't do the homework and just give answers; we guide people to solutions.

The OP was making progress and probably would have learned more if s/he had been required to work through what you gave her/him.

I thought that was posted by the TS! Thanks for pointing this out. I have "unlike" the post b

 

The OP was making progress and probably would have learned more if s/he had been required to work through what you gave her/him.

I did not provide a solution, but merely restated the problem (with color coding). Sometimes the problem itself just tells you what the solution is. Why make it more difficult than that?

 

I did not provide a solution

What would you call this?

Sometimes the problem itself just tells you what the solution is. Why make it more difficult than that?

That's where we were trying to guide the OP...

 

hello All,

let me retry,all the responses so far got me more confused,
i appreciate everyone.
my intent was not to include "don`t care",thought i could bring it in.as earlier advised,i will have to re-read the question to enable correct my error.

Your truth table has 16 rows. Go through each row, one by one, and ask yourself if the alarm should be on or off (or whether you don't care) for each situation. Ask yourself this question in human terms. For instance, for the bottom row you would ask your self, "Do I want the alarm on or off if he engine is running, the door is open, the headlamps are one, and the key is in the ignition?" If the answer is, "Yes," put a '1' in the Alarm column. If the answer is, "No," put a '0' there. Only if the answer is either, "I don't care," or "That condition can't happen," do you put a '*'.

If you put a '*' in any row, you should be able to explain WHY you don't care and state any assumptions that your explanation relies on.

 

What would you call this?

That is a semi-symbolic representation of the previous sentence, which itself was a restatement of the original problem in a single sentence. It is gratifying to know that you think it is the solution because that just reinforces the notion that the problem itself is telling you what the solution is.

Now perhaps you can answer my question, "Why make it any more difficult than that?"

Of course, you may say that the TS needs to learn how to make a truth table sometime; and that would have some merit, which is why I waited until the third page of comments, rather than post early on.

 

It is gratifying to know that you think it is the solution because that just reinforces the notion that the problem itself is telling you what the solution is.

Did you notice the moderator note attached to your post? At least one other person thinks you gave the answer instead of guiding.

Now perhaps you can answer my question, "Why make it any more difficult than that?"

No one said the problem was difficult or that we're intentionally trying to make it more difficult than it is.

When the OP posted the problem, he didn't give us his educational background. So my first recommendation was a truth table and Kmap. Then it became clearer that he hadn't learned how to use Kmaps. Not knowing the types of problems he had been given to this point, it was unclear if he was supposed to draw a truth table and use some method for generating the equation without Kmaps or if he was supposed to reason it out as you did. Since he eventually drew a truth table, that seems to have eliminated the method you chose.

In high school, I once solved a physics problem using intuition instead of a formula. The teacher wanted the formula to be used and my answer, though correct, was marked wrong. This is the burden we have when trying to guide students to solutions. We need to do it using the method the instructor wants; not what we want.

 

@RBR1317

Current elementary students face the dilemma of distinguishing from what we want to do and what the instructor wants. Every day.

Common core math very specifically outlines how a math question should be answered. A response of 4x9=36 would be marked incorrect. An explanation using a grid or by using groups of counters would be expected.

I have taught in the elementary classroom. So I know.

This long diatribe is to support several members belief that you "gave away" the answer. The opportunity for the TS was taken from him. He lost the opportunity to learn how to state the problem - as you did!

The approach taken in the Homework Help section is different than other forums. All the members are asking us that you learn and respect that difference.

 

That is a semi-symbolic representation of the previous sentence, which itself was a restatement of the original problem in a single sentence. It is gratifying to know that you think it is the solution because that just reinforces the notion that the problem itself is telling you what the solution is.

Now perhaps you can answer my question, "Why make it any more difficult than that?"

Of course, you may say that the TS needs to learn how to make a truth table sometime; and that would have some merit, which is why I waited until the third page of comments, rather than post early on.

What the TS needs to learn is how to extract the solution from the problem -- that IS the entire point of a problem like this. There is a reason that the problem didn't say to design a circuit that implements F = A and (B or C). Consider that the TS has almost certainly seen problems like this worked in class and in their text. But something hasn't quite clicked. Why do you think that seeing one more problem worked out for them is going to change that? It almost certainly isn't. What it is most likely to do is make the TS think that they understand it -- until they discover that they don't when the exam comes around.

The TS needs to struggle with figuring out how to extract the key information from the problem and synthesize a solution for himself with only sparse guidance, primarily by pointing out missteps, from the outside. He was making progress in that direction, until you barged in and robbed him of the opportunity to complete that journey.

 

The TS needs to struggle with figuring out how to extract the key information from the problem and synthesize a solution for himself with only sparse guidance, primarily by pointing out missteps, from the outside. He was making progress in that direction, until you barged in and robbed him of the opportunity to complete that journey.

So let me be more direct. The TS was given poor advice from the beginning that constructing a truth table was the appropriate method for synthesizing a solution to this problem. Given that the TS was making progress in that direction, the next step in the sequence would have been minimization - and the TS is clearly not prepared for that at this time. So how did you imagine that the TS would complete that journey?

 

That was not the only advice the TS was given. If you read the entire thread, he had nearly completed his own description that closely paralleled yours. He was also given advice to create a kmap and was repeatedly told that was not necessary.

He was making progress. His main sticking point was identifying the outputs. That could have been resolved.

This thread did tend toward chaos. I limited my participation because of that, in particular the kmap issue. However, another took up just when the noise had subsided and is an excellent teacher.

Then all our efforts came to be worth nothing, because instead of teaching, he got the answer directly. He is happy for now. You are happy. But the TS joy may come to an abrupt end at exam time.