Re: Modelling Cost of Travel Paths Between Towns

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-- 
<%= Clinton Gallagher, "Twice the Results  -- Half the Cost"
         Architectural & e-Business Consulting -- Software Development
         NET csgallagher_at_REMOVETHISTEXTmetromilwaukee.com
         URL http://www.metromilwaukee.com/clintongallagher/


"Alan" <not.me_at_uhuh.rcn.com> wrote in message
news:ZhBjd.4230$EE3.2171_at_trndny09...


>

> "Neo" <neo55592_at_hotmail.com> wrote in message

> news:4b45d3ad.0411071807.4cbd51f0_at_posting.google.com...


> > www.xdb2.com/Example/Ex112.asp demos how to represent things needed to

> > calculate the cost of traveling between any two towns via multiple

> > paths. The example allows the path between any two towns to be uni or

> > bi-directional. The example allows the specification of travel cost

> > during any time period of each weekday.

> >

> > More specifically, the example represents the following things: Four

> > towns named a, b, c, d (imagine them forming a square). There are

> > paths from a to b, b to c, c to d and d to a. There are also opposite

> > paths from a to d, d to c, c to b and b to a. In addition, there are

> > two uni-directional cross paths, one from a to c and the second from b

> > to d. The cost of travel from town a to town b on Monday between 00:00

> > and 24:00 is 1.00.

> >

> > The script below stores above things:

> >

> > // Create towns a, b, c, d

> > CREATE2 *town.cls = thing;

> > CREATE2 *a.cls = town;

> > CREATE2 *b.cls = town;

> > CREATE2 *c.cls = town;

> > CREATE2 *d.cls = town;

> >

> > // Create directional verb "to"

> > // which leads to lower level (aka creature)

> > CREATE2 *goto.cls = verb;

> > CREATE2 goto.vbType = cr;

> >

> > // Create a square shaped graph

> > // Note: outer paths are bi-dir

> > CREATE2 a.goto = b;

> > CREATE2 b.goto = a;

> >

> > CREATE2 b.goto = c;

> > CREATE2 c.goto = b;

> >

> > CREATE2 c.goto = d;

> > CREATE2 d.to = c;

> >

> > CREATE2 d.goto = a;

> > CREATE2 a.goto = d;

> >

> > // Note: inner cross paths are uni-dir

> > CREATE2 a.goto = c;

> > CREATE2 b.goto = d;

> >

> > // Create weekdays

> > CREATE2 *weekday.cls = thing;

> >

> > // Create start time of day (inclusive)

> > CREATE2 *start.cls = thing;

> >

> > // Create end time of day (exclusive)

> > CREATE2 *end.cls = thing;

> >

> > // Create costs

> > CREATE2 *cost.cls = thing;

> >

> > // Create it cost 1.00 to go from town a to town b

> > // on monday between 00:00 and 24:00

> > CREATE2 (a.goto=b).weekday = +monday;

> > CREATE2 ((a.goto=b).weekday=monday).start = +00:00;

> > CREATE2 (((a.goto=b).weekday=monday).start=00:00).end = +24:00;

> > CREATE2 ((((a.goto=b).weekday=monday).start=00:00).end=24:00).cost =

> > +1.00;

>

> Let us analyze:

> * Neo has stored the word "monday" 4 times.

> * Neo has stored letters a, b, c, d more times than I care to count.

> Therefore,  Neo is practicing redundancy.

>

> * Neo has stored program code as data. Neo is practicing Object

Orientation.


>

> * What happens when trip goes to 64 towns in three months, visiting some

> towns more than once? Answer: Neo has stored big headache and carpal

tunnel


> syndrome.

>

> Here is some SQL for Neo to learn:

>

> INSERT INTO neo VALUES 'common sense', 'integrity', 'honesty';

> UPDATE neo SET pocketbook = pocketbook - 1000;

>

>