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#author("2022-12-30T17:57:57+09:00","default:LMNtal","LMNtal") #author("2023-03-13T15:40:11+09:00","default:LMNtal","LMNtal") //[[Documentation]] *Hyperlinks and hypergraphs [#se1fd52b] LMNtal links represent point-to-point connection between atoms and form an ordinary graph. In some applications, however, natural modeling calls for '''hyperlinks''', namely links that interconnect more than two atoms. A graph structure with hyperlinks forms a '''(hierarchical) hypergraph'''. Accordingly, LMNtal now provides the syntax and operations for hypergraphs. The language with this extension is also called HyperLMNtal. **Creating a hyperlink [#hcd901f8] A hyperlink is created by a ''new'' construct specified in a guard. hoge. hoge :- new($h) | a($h), b($h). Since each hyperlink can be regarded as a unary atom with a fresh local name, we use the syntax of process contexts (starting with a '$') to represent it. Another view of hyperlinks is a generalization of ordinary links, and they can be written also by attaching '!' to link names as hoge. hoge :- a(!H), b(!H). or just a(!H), b(!H). The result of all the above programs will be a(!H4), b(!H4). That is, a hyperlink will be printed as a '!H' followed by a system-generated hexadecimal number. **Type checking [#i375b878] The type constraint ''hlink''($x) checks if $x represents a hyperlink. main. main :- new($x) | a($y). a($x) :- hlink($x) | b($x,$x). or a(!Y). a(!X) :- b(!X,!X). Result: b(!H4,!H4). **Equality checking [#gd567c1c] Since an occurrence of a hyperlink is regarded as a unary atom with a special private name, the constructs ''=='' and ''\=='' can be used for comparing two hyperlinks, e.g., a($x), b($y) :- hlink($x), hlink($y), $x == $y | ok. The above rule can be written also as a($x), b($x) :- ok. or a(!X), b(!X) :- ok. **Fusing two hyperlinks [#e554f0f3] Two hyperlinks can be fused into one using the "''><''" operator. main. main :- new($x), new($y) | a($x), b($z). a($x), b($y) :- $x \== $y | ab($x,$y), $x >< $y. or a(!X), b(!Z). a(!X), b(!Y) :- !X \== !Y | ab(!X,!Y), !X >< !Y. If $x and $y represent different hyperlinks (i.e., have different hyperlink names), they will be merged into one; that is, they are made to have the same hyperlink name. **Number of occurrences [#hc2d2626] The ''num'' construct in a guard will return the number of occurrences of the specified hyperlink. main. main :- new($x) | a($x), b($x). a($h) :- $n = num($h) | occurrences($n). or a(!X), b(!X). a(!H) :- $n = num(!H) | occurrences($n). Result: b(!H4), occurrences(2). Another use: a(!X). a(!H) :- num(!H) < 5 | a(!H), a(!H). Result: a(!H4), a(!H4), a(!H4), a(!H4), a(!H4). Yet another use: flag(!X), a(!X), a(!X), a(!X), a(!X), a(!X). a(!H) :- . flag(!H) :- num(!H) =:= 1 | ok. Result: ok. // ok is created when all a(!H1)'s are removed In this way, using hyperlinks, one can check the '''absence''' of a particular hyperlink. *How to use [#nade49a7] **LaViT [#qcec53b9] When you execute your program under LaViT (recommended), select the Option tab and turn on the following checkboxes: - Slimcode Compile Option: ''--slimcode'' and ''--hl-opt'' - Compile Option: ''--slimcode'' and ''--hl-opt'' - Slim Option: ''--hl'' Please see below for the details of those options. **Compiling [#nd78cdd2] Currently, programs with hyperlinks can be executed only under SLIM. To compile them, both ''--slimcode'' and ''--hl'' (or ''--hl-opt'') options need be specified, e.g., lmntal --slimcode --hl hoge.lmn > hoge.il - ''--hl'' : turn on hyperlinks. - ''--hl-opt'' : turn on hyperlinks and optimize graph matching using hyperlink connection. **Execution [#aff38a8e] Specify ''--hl'' when running SLIM, e.g., slim --hl --show-hl hoge.il - ''--hl'' : turn on hyperlinks. - ''--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.
