- 1.0 20080502 (elf) Initial release.

This extension provides procedures for operating on disjoint sets. For an explanation of where and why this is useful, consult an algorithms textbook. (Chapter 22 of Cormen is a good starting point.)

The total running time of any sane sequence of disjoint set operations should be O(n) in this implementation.

**procedure:**(make-disjoint-set NUM-ELEMENTS)-
Creates a new disjoint set object.

`NUM-ELEMENTS`must be a positive integer. There are`NUM-ELEMENTS`partitions initially. **procedure:**(disjoint-set? OBJ)-
Returns

`#t`if`OBJ`is a disjoint set object. **procedure:**(disjoint-set-ref DISJOINT-SET ELEM)-
Returns the representative element of the set containing

`ELEM`. **procedure:**(disjoint-set-unify! DISJOINT-SET ELEM1 ELEM2)-
Unifies the sets containing elements

`ELEM1`and`ELEM2`. An error is signalled if the sets are already unified. **procedure:**(disjoint-set-merge! DISJOINT-SET SUB1 SUB2)-
Another name for

`disjoint-set-unify!`, above.

**procedure:**(disjoint-set-equal? DISJOINT-SET ELEM1 ELEM2)-
Returns

`#t`if`ELEM1`and`ELEM2`are members of the same set. **procedure:**(disjoint-set-members DISJOINT-SET ELEM)-
Returns a list of all members of the set containing

`ELEM`. NOTE: This procedure should be used only for debugging purposes, and is not considered a "sane" operation. **procedure:**(disjoint-set-elements DISJOINT-SET)-
Returns the number of unique elements (not unique sets) in

`DISJOINT-SET`. **procedure:**(disjoint-set-sets DISJOINT-SET)-
Returns the number of unique sets currently in

`DISJOINT-SET`. **procedure:**(disjoint-set-unified? DISJOINT-SET)-
Returns

`#t`if all elements are in the same set. **procedure:**(disjoint-set->list DISJOINT-SET)-
Creates a list of lists, where each sublist corresponds to a unique set.

None known

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