Rocksolid Light - comp.lang.prolog - GO CITY1 CITY2 .... with BACKTRACKING!

GO CITY1 CITY2 .... with BACKTRACKING!

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Subject: GO CITY1 CITY2 .... with BACKTRACKING!
From: grahamcooper7@gmail.com (Graham Cooper)
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by: Graham Cooper - Tue, 9 May 2023 11:46 UTC

it tries all the odd combinations until it arrives at

1 -- 2-- 4 -- 6

go FROM TO*
rd 1 3
rd 2 4
rd 3 5
rd 4 6
rd 5 7
rd 1 2

------ 1 0/0 -----
query :- go 1 6
------------
---------- BEGIN 1 ---------
go 1 6
1>>> FROM = 1
1>>> TO = 6

------ 2 0/0 -----
go FROM TO :- rd FROM TO
------------
---------- BEGIN 2 ---------
rd FROM TO
1> FROM = 1
1> TO = 6
NOT FOUND

****** 2 ******
FROM = 1 TO = 6
****************

PROGRAM 2

------ 3 1/1 -----
go FROM TO :- rd FROM MID go MID TO
------------
---------- BEGIN 3 ---------
rd FROM MID
2> FROM = 1
3>> MID = 3
---------- BEGIN 4 ---------
go MID TO
3> MID = 3
3> TO = 6
4>>> FROM = 3
4>>> TO = 6

------ 5 0/0 -----
go FROM TO :- rd FROM TO
------------
---------- BEGIN 5 ---------
rd FROM TO
4> FROM = 3
4> TO = 6
NOT FOUND

****** 5 ******
FROM = 3 TO = 6
****************

PROGRAM 2

------ 6 1/1 -----
go FROM TO :- rd FROM MID go MID TO
------------
---------- BEGIN 6 ---------
rd FROM MID
5> FROM = 3
6>> MID = 5
---------- BEGIN 7 ---------
go MID TO
6> MID = 5
6> TO = 6
7>>> FROM = 5
7>>> TO = 6

------ 8 0/0 -----
go FROM TO :- rd FROM TO
------------
---------- BEGIN 8 ---------
rd FROM TO
7> FROM = 5
7> TO = 6
NOT FOUND

****** 8 ******
FROM = 5 TO = 6
****************

PROGRAM 2

------ 9 1/1 -----
go FROM TO :- rd FROM MID go MID TO
------------
---------- BEGIN 9 ---------
rd FROM MID
8> FROM = 5
9>> MID = 7
---------- BEGIN 10 ---------
go MID TO
9> MID = 7
9> TO = 6
10>>> FROM = 7
10>>> TO = 6

------ 11 0/0 -----
go FROM TO :- rd FROM TO
------------
---------- BEGIN 11 ---------
rd FROM TO
10> FROM = 7
10> TO = 6
NOT FOUND

****** 11 ******
FROM = 7 TO = 6
****************

PROGRAM 2

------ 12 1/1 -----
go FROM TO :- rd FROM MID go MID TO
------------
---------- BEGIN 12 ---------
rd FROM MID
11> FROM = 7
NOT FOUND

****** 12 ******
FROM = 7 TO = 6
****************
NOT FOUND
BACKTRACK

NOT FOUND

****** 9 ******
FROM = 5 TO = 6 MID = 7
****************
NOT FOUND
BACKTRACK

NOT FOUND

****** 6 ******
FROM = 3 TO = 6 MID = 5
****************
NOT FOUND
BACKTRACK

15>> MID = 2
---------- BEGIN 16 ---------
go MID TO
15> MID = 2
15> TO = 6
16>>> FROM = 2
16>>> TO = 6

------ 17 0/0 -----
go FROM TO :- rd FROM TO
------------
---------- BEGIN 17 ---------
rd FROM TO
16> FROM = 2
16> TO = 6
NOT FOUND

****** 17 ******
FROM = 2 TO = 6
****************

PROGRAM 2

------ 18 1/1 -----
go FROM TO :- rd FROM MID go MID TO
------------
---------- BEGIN 18 ---------
rd FROM MID
17> FROM = 2
18>> MID = 4
---------- BEGIN 19 ---------
go MID TO
18> MID = 4
18> TO = 6
19>>> FROM = 4
19>>> TO = 6

------ 20 0/0 -----
go FROM TO :- rd FROM TO
------------
---------- BEGIN 20 ---------
rd FROM TO
19> FROM = 4
19> TO = 6

****** 20 ******
FROM = 4 TO = 6
****************

****** 18 ******
FROM = 2 TO = 6 MID = 4
****************

****** 3 ******
FROM = 1 TO = 6 MID = 3
****************

YES

But Captain -- the engines can't take this much longer!

devel / comp.lang.prolog / GO CITY1 CITY2 .... with BACKTRACKING!

Subject	Author
GO CITY1 CITY2 .... with BACKTRACKING!	Graham Cooper