?
Solved

Can It Be In Horn Form

Posted on 2010-11-10
12
Medium Priority
?
467 Views
Last Modified: 2012-06-27
I'm trying to understand whether R => (E <==> C) can be expressed in Horn form. How do I deal with this?
0
Comment
Question by:JCW2
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 6
  • 6
12 Comments
 
LVL 37

Accepted Solution

by:
TommySzalapski earned 2000 total points
ID: 34108276
For Horn form I make a truth table with each of the variables and the main clause I'm testing.
For all the Fs in the main clause column all the literals must be F in the same row except for one.
So your equations truth table looks like the following. Can it go into Horn form? Look at the F rows in the last column and tell me.
0
 

Author Comment

by:JCW2
ID: 34115019
By main clause, do you mean R?
0
 
LVL 37

Assisted Solution

by:TommySzalapski
TommySzalapski earned 2000 total points
ID: 34115139
No. The main clause is R => (E <==> C)
The easiest way to set up the truth table would probably be to put columns for
R, E, C, E<==>C, and R=>(E<==>C)
Then circle all the rows with Fs in the last column. Ignore the E<==>C column when checking for Horn form of course. Just check the literals. I add that column because I don't want to try to do it all in my head.
Generate the truth table and post it so I can help you make sure you are doing it right. I'll be on for a couple hours yet.
0
Get proactive database performance tuning online

At Percona’s web store you can order full Percona Database Performance Audit in minutes. Find out the health of your database, and how to improve it. Pay online with a credit card. Improve your database performance now!

 

Author Comment

by:JCW2
ID: 34115570
Using E <==> C as the main clause, I don't think I can express my problem in Horn form. Am I correct?
0
 

Author Comment

by:JCW2
ID: 34115580
Disregard the last comment.
0
 
LVL 37

Assisted Solution

by:TommySzalapski
TommySzalapski earned 2000 total points
ID: 34115614
It is true that E<==>C cannot be expressed in Horn form. So you're probably doing it right.
0
 

Author Comment

by:JCW2
ID: 34115701
From what I can see, the relevant rows are

T T F - F and
T F T - F.

Therefore, we can not express the propositional sentence in Horn form.
Is this correct?
0
 
LVL 37

Assisted Solution

by:TommySzalapski
TommySzalapski earned 2000 total points
ID: 34115731
100% correct.
0
 

Author Comment

by:JCW2
ID: 34115794
Another thing: is it possible for a sentence to be expressed in Horn form if all literals are F in the proper row?
0
 
LVL 37

Assisted Solution

by:TommySzalapski
TommySzalapski earned 2000 total points
ID: 34115925
Yes. Sorry. Should have read:

For Horn form I make a truth table with each of the variables and the main clause I'm testing.
For all the Fs in the main clause column all or all but one of the literals must be F in the same row.
0
 

Author Closing Comment

by:JCW2
ID: 34115958
Thank you for your help.
0
 
LVL 37

Expert Comment

by:TommySzalapski
ID: 34115981
A Horn clause has AT MOST one positive literal.
A definite clause has EXACTLY one positive literal.
So the definite clause would not work if the whole row was Ts, but Horn could.
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article provides a brief introduction to tissue engineering, the process by which organs can be grown artificially. It covers the problems with organ transplants, the tissue engineering process, and the current successes and problems of the tec…
Q&A with Course Creator, Mark Lassoff, on the importance of HTML5 in the career of a modern-day developer.
In this fifth video of the Xpdf series, we discuss and demonstrate the PDFdetach utility, which is able to list and, more importantly, extract attachments that are embedded in PDF files. It does this via a command line interface, making it suitable …
In this seventh video of the Xpdf series, we discuss and demonstrate the PDFfonts utility, which lists all the fonts used in a PDF file. It does this via a command line interface, making it suitable for use in programs, scripts, batch files — any pl…
Suggested Courses

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question