Solved

Can It Be In Horn Form

Posted on 2010-11-10
12
461 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
  • 6
  • 6
12 Comments
 
LVL 37

Accepted Solution

by:
TommySzalapski earned 500 total points
Comment Utility
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
Comment Utility
By main clause, do you mean R?
0
 
LVL 37

Assisted Solution

by:TommySzalapski
TommySzalapski earned 500 total points
Comment Utility
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
 

Author Comment

by:JCW2
Comment Utility
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
Comment Utility
Disregard the last comment.
0
 
LVL 37

Assisted Solution

by:TommySzalapski
TommySzalapski earned 500 total points
Comment Utility
It is true that E<==>C cannot be expressed in Horn form. So you're probably doing it right.
0
Enabling OSINT in Activity Based Intelligence

Activity based intelligence (ABI) requires access to all available sources of data. Recorded Future allows analysts to observe structured data on the open, deep, and dark web.

 

Author Comment

by:JCW2
Comment Utility
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 500 total points
Comment Utility
100% correct.
0
 

Author Comment

by:JCW2
Comment Utility
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 500 total points
Comment Utility
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
Comment Utility
Thank you for your help.
0
 
LVL 37

Expert Comment

by:TommySzalapski
Comment Utility
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

How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

Join & Write a Comment

Suggested Solutions

Article by: Nicole
This is a research brief on the potential colonization of humans on Mars.
Although it can be difficult to imagine, someday your child will have a career of his or her own. He or she will likely start a family, buy a home and start having their own children. So, while being a kid is still extremely important, it’s also …
In this fourth video of the Xpdf series, we discuss and demonstrate the PDFinfo utility, which retrieves the contents of a PDF's Info Dictionary, as well as some other information, including the page count. We show how to isolate the page count in a…
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 …

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

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now