On Sat, May 10, 2008 at 3:45 PM, katie678 <[EMAIL PROTECTED]>
wrote:
>
> Hi,
>
> I am complety new to Jess and am in desperate need of help please.
Hi Katie,
Here is a list of issues that caught my eye:
1. If you have a function B that depends on function A, then function A
*must* be defined in your Jess script *before* function B, else B will not
"know about" A.
Look at your code carefully to spot this one.
2. All LHS patterns are implicitly joined with an (and). There is no need
to use (and <pattern 1> <pattern 2> ... <pattern n> ) in your rules. Fix
all the rules that do this.
3. Don't use the (or) connective to simply match facts having alternative
slot values. If you want to match on (foo) facts with a slot called "value"
such that value = 5, 10, or 15 you would write:
(defrule find-foos
(foo (value ?v&5|10|25))
=>
;; do something interesting here
)
Fix all the rules where you have done this.
4. If you want a fact matched over a range of slot values, then you use
predicate constraints like so:
Match all (foo) fact with value between 1 and 3:
(defrule find-foos-from-1-to-3
(foo (value ?v&:(>= ?v 1)&:(< ?v 4)))
=>
;; Do something interesting here
)
Make these corrections, too.
5. When you have two or more rules for which there will never be more than
one fact that activates more than one rule at a time, there is no need to
enforce
activation order using salience -- I think this is where your code diverges
from the Tax Adviser example in "Jess in Action". The tax adviser will
actually recommend multiple
forms whereas you just recommend one course of action. When you do use
salience, as in all programming, avoid using unbound "magic numbers" like
100000 and 70000.
These are arbitrary and just bad karma -- the danger is where do you stop
once you start? 100001, 100002, 70001, etc?
Take a look at the article on the Jess wiki
http://www.jessrules.com/jesswiki/view?SalienceUsageTips and in the
documentation http://www.jessrules.com/jess/docs/71/rules.html#salienceregarding
salience.
Less important items...
1. You've got some typos in your questions that make answering them
awkward. For example:
"Do you want to work full time after homes?" makes no sense.
"How many homes a week do you want to work?" -- clearly you meant "hours
a week".
Go through all your questions and edit them.
2. Good programmers error-trap their code for bad inputs. Any place that
you are expecting numerical input (asking about ages, dollars, etc.) run the
input
through the (numberp) function. (numberp) stands for number-parse, and
gives back a boolean TRUE if its argument parses to any number.
3. Omit defining (defglobal ?*crlf* = ...) since it's part of Jess now
anyway. Just use the symbol "crlf" anywhere you want a
carriage-return-linefeed.
It is important that you make these changes and that I just not give you my
corrected solution -- I hope nobody actually does this!
Once I fixed these issues, your program seemed to run just fine.
I hope this helps!
Cheers,
Jason
-----------------------------------------------------------
Jason Morris
Morris Technical Solutions LLC
[EMAIL PROTECTED]
(517) 304-5883
