Backup of Hyperlinks(No. 2)

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Hyperlinks

LMNtal links represent point-to-point connection between atoms and form an ordinary graph. In some applications, however, we may want hyperlinks, namely links that interconnect more than two atoms and form a hypergraph.

LMNtal provides syntax and operations for hypergraphs, which will be described below. Currently, hyperlinks are supported by the slim runtime in the ordinary (as opposed to non-deterministic) execution mode.

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Creating a hyperlink

A hyperlink is created by a "new" construct specified in a guard.

hoge.
hoge :- new($h) | a($h), b($h).
*--> a(!1), b(!1).

Each hyperlink is given a fresh private name, which will be printed as a "!" followed by a hexadecimal number.

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Type checking

The type constraint "hlink($x)" checks if $x represents a hyperlink.

main.
main :- new($x) | a($x).
a($x) :- hlink($x) | b($x).
*--> b(!1).

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Equality checking

An occurrence of a hyperlink is regarded as a unary atom (with a special, private name). Therefore, the constructs == and \= can be used for comparing two hyperlinks, e.g.,

a($x), b($y) :- hlink($x), hlink($y), $x == $y | ok.

In addition, the above rule can be written as

a($x), b($x) :- ok.

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Fusing two hyperlinks

Two hyperlinks can be fused into one using the "><" operator.

a(!1), b(!2).
a($x), a($y) :- $x \= $y | a($x), b($y), $x >< $y.

If $x and $y represent different hyperlinks (i.e., have different hyperlink names), they will be merged into one; that is, they are made to have the same hyperlink name.

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Number of occurrences

The "num" construct in a guard will return the number of occurrences of the specified hyperlink.

a(!1), b(!1).
a($h) :- $n = num($h) | number($n).
*--> b(!1), number(2).

Another use

a(!1).
a($h) :- $n = num($h), $n < 5 | a($h), a($h).
*--> a(!1), a(!1), a(!1), a(!1), a(!1).

Yet another use

flag(!1), a(!1), a(!1), a(!1), a(!1).
a($h) :- hlink($h) | .
flag($h) :- $n = num($h), $n =:= 1 | ok.
*--> ok. // ok is created when all a(!1)'s are removed

Thus, using hyperlinks, one can check the absence of a particular atom.

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How to use

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Compiling

Currently, programs with hyperlinks can be executed only under slim. To compile, both --slimcode and --hl (or --hl-opt) options need be specified, e.g.,

lmntal --slimcode --hl hoge.lmn > hoge.il

--hl : uses hyperlinks.

--hl-opt : uses hyperlinks and optimizes matching

 --- &#20013;&#38291;&#21629;&#20196;findproccxt&#12364;&#25407;&#20837;&#12373;&#12428;&#12427;
 --- &#12460;&#12540;&#12489;&#12395;&#33258;&#21205;&#30340;&#12395;hlink&#21046;&#32004;&#12434;&#25407;&#20837;&#12371;&#12392;&#12391;&#12289;ground&#23550;ground&#12398;&#27083;&#36896;&#27604;&#36611;&#12434;&#12501;&#12449;&#12531;&#12463;&#12479;&#23550;&#12501;&#12449;&#12531;&#12463;&#12479;&#12391;&#28168;&#12414;&#12379;&#12427;&#12424;&#12358;&#12395;&#12375;&#12390;&#12356;&#12427;
 ---&#12385;&#12394;&#12415;&#12395;&#21516;&#21517;&#22411;&#20184;&#12365;&#12503;&#12525;&#12475;&#12473;&#25991;&#33032;&#12399;&#12289;&#20966;&#29702;&#31995;&#20869;&#37096;&#12398;&#12467;&#12540;&#12489;&#12391;&#12399;sameproccxt&#12394;&#12393;&#12392;&#21628;&#31216;

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Executing

Specify --hl when running slim, e.g.,

slim --hl --show-hl hoge.il

--hl : uses hyperlinks
- currently, this cannot be specified with -nd
--show-hl : prints the details of hyperlinks
- Without this option, different occurrences of a hyperlink are printed with the same name.
- With this option, each occurrence of a hyperlink is printed with its own ID. In addition, a table of hyperlink occurrences will be printed.

Backup of Hyperlinks (No. 2)