Re: Demo: Modelling Cost of Travel Paths Between Towns

> Incomplete problem description.
> What is the costs for travel on other days?

In order to keep the example simple, the script only showed the cost of travel between two towns (a to b) in one direction during a specific day of the week (monday), during a specific time period (00:00 to 24:00). The updated script at the end has 4 such entries and should allow one to deduce how to enter additional ones. If you or the original problem poster would like to present more representative data, I can enter it.

> > // Create directional verb "to" 
>
> Documentation error. you actually created the verb "goto"

Thanks.

> > CREATE2 c.goto = d;
> > CREATE2 d.to = c;
> 
> Compile error. no such method as "to"

Thanks! for spotting the semantic (but not syntatic) error. I originally created the script using "to" instead of "goto", but later realized that since the db already has the preposition "to", I would need to use the expression (%.cls=verb & %.name=to) in order to distinguish them making the script longer. During the conversion from "to" to "goto" I made the above significant error.

> Actually all the so-called paths are unidirectional. > You never created a bidirectional "goto" verb.

Didn't need to create a bi-directional verb because two opposite uni-directionals paths form a bi-directional path as in: CREATE2 a.goto = b;
CREATE2 b.goto = a;

If I had created a bi-directional verb, it would be difficult to specify a one way street and different cost/period for each uni-direction.

> > // 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;
> 
> weird operators...is there such a thing as a negative monday?

CREATE2 it.name = monday;  // short cut to relating to each symbol
CREATE2 it.cls = weekday;
CREATE2 (a.goto=b).weekday = monday; // or "(a.goto=b).weekday = it;"

I am open to suggestions for improving XDb2's scripting language.

> Now that you have a design, what problems do you think you can solve 
> with it? (You are not really so uninformed as to suggest this might solve 
> the travelling salesman problem, are you?)

I assumed that people would understand the example only represents the things needed in a db to calculate best path and not the algorithms to do so. However I believe I could code the algorithm. Are you saying that no one has solved this type of problem with RM thus far?

// 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 uni-directional verb "goto"
// 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.goto = 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 =

// Create it cost 1.56 to go from town b to town a
// on tuesday between 08:00 and 17:00

CREATE2 (b.goto=a).weekday = +tuesday;
CREATE2 ((b.goto=a).weekday=tuesday).start = +08:00;
CREATE2 (((b.goto=a).weekday=tuesday).start=08:00).end = +17:00;
CREATE2 ((((b.goto=a).weekday=tuesday).start=08:00).end=17:00).cost =

// Create it cost 2.30 to go from town b to town c
// on wednesday between 09:00 and 15:00

CREATE2 (b.goto=c).weekday = +wednesday;
CREATE2 ((b.goto=c).weekday=wednesday).start = +09:00;
CREATE2 (((b.goto=c).weekday=wednesday).start=09:00).end = +15:00;
CREATE2 ((((b.goto=c).weekday=wednesday).start=09:00).end=15:00).cost

// Create it cost 3.16 to go from town c to town b
// on thursday between 10:00 and 14:00

CREATE2 (c.goto=b).weekday = +thursday;
CREATE2 ((c.goto=b).weekday=thursday).start = +10:00;
CREATE2 (((c.goto=b).weekday=thursday).start=10:00).end = +14:00;
CREATE2 ((((c.goto=b).weekday=thursday).start=10:00).end=14:00).cost =