NAME

         GO::Model::Relationship - relationship between two terms

SYNOPSIS

DESCRIPTION

       a relationship between two GO::Model::Terms

       relationships can be thought of as statements or sentences of the form

         SUBJECT-TERM PREDICATE OBJECT-TERM

       for example,

         "dog" IS_A "animal"

         "G-Protein coupled receptor" IS_A "transmembrane receptor"

       Statements have a subject (i.e. the subject of the sentence/statement), a
       predicate/relationship-type and an object (i.e. the object of the sentence/statement)

       Relationships can also be seen as arcs in a directed graph, with the subject being
       equivalent to the child, and the object equivalent to the parent. The arc is labeled with
       the predicate/relationship-type.

       A Relationship object currently does not contain an actual pointer to a GO::Model::Term
       object. Instead it stores the ID of that term. This is intended to be used in conjunction
       with the Graph object, or with the database.

   subject_acc
        Title   : subject_acc
        Usage   : $obj->subject_acc($newid)
        Usage   : $currid = $obj->subject_acc()
        Synonyms: subj_acc, acc2, child_acc
        Function: gets or sets the identifier for the child/subject term
        Example :
        Returns : value of subject_acc (string)
        Args    : on set, new value (string)

       All Relationships can be thought of "subject-predicate-object" statements. The statement
       is *about* the subject, and states something about the relationship *to* the object.

       For example, the if we have a Relationship:

         cell
           ^
           |
           | [part_of]
           |
        cell nucleus

       This is a statement about cell nuclei in general, so "cell nucleus" is the subject
       (sometimes called the child node). The Relationship tells us that all cell nuclei are
       part_of some cell, so the object of the relationship (sometimes called the parent node) is
       "cell"

   object_acc
        Title   : object_acc
        Usage   : $obj->object_acc($newid)
        Usage   : $currid = $obj->object_acc()
        Synonyms: obj_acc, acc1, parent_acc
        Function: gets or sets the identifier for the parent/object term
        Example :
        Returns : value of object_acc (string)
        Args    : on set, new value (string)
        See Also: subj_acc

   type
        Title   : type
        Usage   : $obj->type($newval)
        Usage   : $currval = $obj->type()
        Synonyms:
        Function: gets or sets the relationship type (a string)
        Example :
        Returns : value of type (string)
        Args    : on set, new value (string)

       Currently any string is allowed; in future the type string may be constrained to come from
       a controlled vocabulary of relationship types