rishi/scryer-prolog
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Migrate from Markdown to Djot

Browse Source
This commit is contained in:
Adrián Arroyo Calle
2023-01-19 21:15:25 +01:00
parent 84583da5b8
commit 46d1e3bee3
11 changed files with 334 additions and 243 deletions
Download Patch File Download Diff File Expand all files Collapse all files

157
src/lib/ugraphs.pl
View File

@@ -61,14 +61,14 @@ neighbours of each vertex are also in standard order (as produced by
sort). This form is convenient for many calculations.
A new UGraph from raw data can be created using
vertices\_edges\_to\_ugraph/3.
`vertices_edges_to_ugraph/3`.
Adapted to support some of the functionality of the SICStus ugraphs
library by Vitor Santos Costa.
Ported from YAP 5.0.1 to SWI-Prolog by Jan Wielemaker.
Ported from SWI-Prolog to Scryer by Adrián Arroyo Calle
Ported from SWI-Prolog to Scryer by [Adrián Arroyo Calle](https://adrianistan.eu)
License: BSD-2 or Artistic 2.0
*/
@@ -81,8 +81,10 @@ License: BSD-2 or Artistic 2.0
%
% Unify Vertices with all vertices appearing in Graph. Example:
%
% ?- vertices([1-[3,5],2-[4],3-[],4-[5],5-[]], L).
% L = [1, 2, 3, 4, 5]
% ```
% ?- vertices([1-[3,5],2-[4],3-[],4-[5],5-[]], L).
% L = [1, 2, 3, 4, 5]
% ```
vertices([], []) :- !.
vertices([Vertex-_|Graph], [Vertex|Vertices]) :-
@@ -97,14 +99,18 @@ vertices([Vertex-_|Graph], [Vertex|Vertices]) :-
% edges will appear in Vertices but not in Edges. Moreover, it is
% sufficient for a vertice to appear in Edges.
%
% ?- vertices_edges_to_ugraph([],[1-3,2-4,4-5,1-5], L).
% L = [1-[3,5], 2-[4], 3-[], 4-[5], 5-[]]
%
% ```
% ?- vertices_edges_to_ugraph([],[1-3,2-4,4-5,1-5], L).
% L = [1-[3,5], 2-[4], 3-[], 4-[5], 5-[]]
% ```
%
% In this case all vertices are defined implicitly. The next
% example shows three unconnected vertices:
%
% ?- vertices_edges_to_ugraph([6,7,8],[1-3,2-4,4-5,1-5], L).
% L = [1-[3,5], 2-[4], 3-[], 4-[5], 5-[], 6-[], 7-[], 8-[]]
% ```
% ?- vertices_edges_to_ugraph([6,7,8],[1-3,2-4,4-5,1-5], L).
% L = [1-[3,5], 2-[4], 3-[], 4-[5], 5-[], 6-[], 7-[], 8-[]]
% ```
vertices_edges_to_ugraph(Vertices, Edges, Graph) :-
sort(Edges, EdgeSet),
@@ -119,8 +125,10 @@ vertices_edges_to_ugraph(Vertices, Edges, Graph) :-
% Unify NewGraph with a new graph obtained by adding the list of
% Vertices to Graph. Example:
%
% ?- add_vertices([1-[3,5],2-[]], [0,1,2,9], NG).
% NG = [0-[], 1-[3,5], 2-[], 9-[]]
% ```
% ?- add_vertices([1-[3,5],2-[]], [0,1,2,9], NG).
% NG = [0-[], 1-[3,5], 2-[], 9-[]]
% ```
% replace with real msort/2 when available
msort_(List, Sorted) :-
@@ -158,10 +166,12 @@ add_empty_vertices([V|G], [V-[]|NG]) :-
% Vertices and all the edges that start from or go to a vertex in
% Vertices to the Graph. Example:
%
% ?- del_vertices([1-[3,5],2-[4],3-[],4-[5],5-[],6-[],7-[2,6],8-[]],
% [2,1],
% NL).
% NL = [3-[],4-[5],5-[],6-[],7-[6],8-[]]
% ```
% ?- del_vertices([1-[3,5],2-[4],3-[],4-[5],5-[],6-[],7-[2,6],8-[]],
% [2,1],
% NL).
% NL = [3-[],4-[5],5-[],6-[],7-[6],8-[]]
% ```
del_vertices(Graph, Vertices, NewGraph) :-
sort(Vertices, V1), % JW: was msort
@@ -195,12 +205,14 @@ split_on_del_vertices(=, _, _, [_|Vs], Vs, _, NG, NG).
% Unify NewGraph with a new graph obtained by adding the list of Edges
% to Graph. Example:
%
% ?- add_edges([1-[3,5],2-[4],3-[],4-[5],
% 5-[],6-[],7-[],8-[]],
% [1-6,2-3,3-2,5-7,3-2,4-5],
% NL).
% NL = [1-[3,5,6], 2-[3,4], 3-[2], 4-[5],
% 5-[7], 6-[], 7-[], 8-[]]
% ```
% ?- add_edges([1-[3,5],2-[4],3-[],4-[5],
% 5-[],6-[],7-[],8-[]],
% [1-6,2-3,3-2,5-7,3-2,4-5],
% NL).
% NL = [1-[3,5,6], 2-[3,4], 3-[2], 4-[5],
% 5-[7], 6-[], 7-[], 8-[]]
% ```
add_edges(Graph, Edges, NewGraph) :-
p_to_s_graph(Edges, G1),
@@ -210,8 +222,10 @@ add_edges(Graph, Edges, NewGraph) :-
%
% NewGraph is the union of Graph1 and Graph2. Example:
%
% ?- ugraph_union([1-[2],2-[3]],[2-[4],3-[1,2,4]],L).
% L = [1-[2], 2-[3,4], 3-[1,2,4]]
% ```
% ?- ugraph_union([1-[2],2-[3]],[2-[4],3-[1,2,4]],L).
% L = [1-[2], 2-[3,4], 3-[1,2,4]]
% ```
ugraph_union(Set1, [], Set1) :- !.
ugraph_union([], Set2, Set2) :- !.
@@ -232,10 +246,12 @@ ugraph_union(>, Head1, Tail1, Head2, Tail2, [Head2|Union]) :-
% Unify NewGraph with a new graph obtained by removing the list of
% Edges from Graph. Notice that no vertices are deleted. Example:
%
% ?- del_edges([1-[3,5],2-[4],3-[],4-[5],5-[],6-[],7-[],8-[]],
% [1-6,2-3,3-2,5-7,3-2,4-5,1-3],
% NL).
% NL = [1-[5],2-[4],3-[],4-[],5-[],6-[],7-[],8-[]]
% ```
% ?- del_edges([1-[3,5],2-[4],3-[],4-[5],5-[],6-[],7-[],8-[]],
% [1-6,2-3,3-2,5-7,3-2,4-5,1-3],
% NL).
% NL = [1-[5],2-[4],3-[],4-[],5-[],6-[],7-[],8-[]]
% ```
del_edges(Graph, Edges, NewGraph) :-
p_to_s_graph(Edges, G1),
@@ -243,7 +259,7 @@ del_edges(Graph, Edges, NewGraph) :-
%% graph_subtract(+Set1, +Set2, ?Difference)
%
% Is based on ord_subtract
% Is based on `ord_subtract/3`
graph_subtract(Set1, [], Set1) :- !.
graph_subtract([], _, []).
@@ -263,8 +279,10 @@ graph_subtract(>, Head1, Tail1, _, Tail2, Difference) :-
%
% Unify Edges with all edges appearing in Graph. Example:
%
% ?- edges([1-[3,5],2-[4],3-[],4-[5],5-[]], L).
% L = [1-3, 1-5, 2-4, 4-5]
% ```
% ?- edges([1-[3,5],2-[4],3-[],4-[5],5-[]], L).
% L = [1-3, 1-5, 2-4, 4-5]
% ```
edges(Graph, Edges) :-
s_to_p_graph(Graph, Edges).
@@ -309,8 +327,10 @@ s_to_p_graph([Neib|Neibs], Vertex, [Vertex-Neib|P], Rest_P) :-
% Generate the graph Closure as the transitive closure of Graph.
% Example:
%
% ?- transitive_closure([1-[2,3],2-[4,5],4-[6]],L).
% L = [1-[2,3,4,5,6], 2-[4,5,6], 4-[6]]
% ```
% ?- transitive_closure([1-[2,3],2-[4,5],4-[6]],L).
% L = [1-[2,3,4,5,6], 2-[4,5,6], 4-[6]]
% ```
transitive_closure(Graph, Closure) :-
warshall(Graph, Graph, Closure).
@@ -336,12 +356,14 @@ warshall([], _, _, []).
%
% Unify NewGraph with a new graph obtained from Graph by replacing
% all edges of the form V1-V2 by edges of the form V2-V1. The cost
% is O(|V|*log(|V|)). Notice that an undirected graph is its own
% is O(|V|\*log(|V|)). Notice that an undirected graph is its own
% transpose. Example:
%
% ?- transpose([1-[3,5],2-[4],3-[],4-[5],
% 5-[],6-[],7-[],8-[]], NL).
% NL = [1-[],2-[],3-[1],4-[2],5-[1,4],6-[],7-[],8-[]]
% ```
% ?- transpose([1-[3,5],2-[4],3-[],4-[5],
% 5-[],6-[],7-[],8-[]], NL).
% NL = [1-[],2-[],3-[1],4-[2],5-[1,4],6-[],7-[],8-[]]
% ```
transpose_ugraph(Graph, NewGraph) :-
edges(Graph, Edges),
@@ -358,8 +380,10 @@ flip_edges([Key-Val|Pairs], [Val-Key|Flipped]) :-
% Compose NewGraph by connecting the _drains_ of LeftGraph to the
% _sources_ of RightGraph. Example:
%
% ?- compose([1-[2],2-[3]],[2-[4],3-[1,2,4]],L).
% L = [1-[4], 2-[1,2,4], 3-[]]
% ```
% ?- compose([1-[2],2-[3]],[2-[4],3-[1,2,4]],L).
% L = [1-[4], 2-[1,2,4], 3-[]]
% ```
compose(G1, G2, Composition) :-
vertices(G1, V1),
@@ -401,8 +425,10 @@ compose1(=, V1, Vs1, V1, N2, G2, SoFar, Comp) :-
% acyclic. In the example we show how topological sorting works
% for a linear graph:
%
% ?- top_sort([1-[2], 2-[3], 3-[]], L).
% L = [1, 2, 3]
% ```
% ?- top_sort([1-[2], 2-[3], 3-[]], L).
% L = [1, 2, 3]
% ```
top_sort(Graph, Sorted) :-
vertices_and_zeros(Graph, Vertices, Counts0),
@@ -412,8 +438,8 @@ top_sort(Graph, Sorted) :-
%% top_sort(+Graph, -Sorted, ?Tail) is semidet.
%
% The predicate top\_sort/3 is a difference list version of
% top\_sort/2.
% The predicate `top_sort/3` is a difference list version of
% `top_sort/2`.
top_sort(Graph, Sorted0, Sorted) :-
vertices_and_zeros(Graph, Vertices, Counts0),
@@ -496,13 +522,15 @@ decr_list(Neibs, [_|Vertices], [N|Counts1], [N|Counts2], Zi, Zo) :-
% Neigbours is a sorted list of the neighbours of Vertex in Graph.
% Example:
%
% ?- neighbours(4,[1-[3,5],2-[4],3-[],
% 4-[1,2,7,5],5-[],6-[],7-[],8-[]], NL).
% NL = [1,2,7,5]
% ```
% ?- neighbours(4,[1-[3,5],2-[4],3-[],
% 4-[1,2,7,5],5-[],6-[],7-[],8-[]], NL).
% NL = [1,2,7,5]
% ```
%% neighbors(+Vertex, +Graph, -Neigbours) is det.
%
% Same as neighbours/3
% Same as `neighbours/3`.
neighbors(Vertex, Graph, Neig) :-
neighbours(Vertex, Graph, Neig).
@@ -523,13 +551,15 @@ neighbours(V,[_|G],Neig) :-
%
% Can be used to order a not-connected graph as follows:
%
% top_sort_unconnected(Graph, Vertices) :-
% ( top_sort(Graph, Vertices)
% -> true
% ; connect_ugraph(Graph, Start, Connected),
% top_sort(Connected, Ordered0),
% Ordered0 = [Start|Vertices]
% ).
% ```
% top_sort_unconnected(Graph, Vertices) :-
% ( top_sort(Graph, Vertices)
% -> true
% ; connect_ugraph(Graph, Start, Connected),
% top_sort(Connected, Ordered0),
% Ordered0 = [Start|Vertices]
% ).
% ```
connect_ugraph([], 0, []) :- !.
connect_ugraph(Graph, Start, [Start-Vertices|Graph]) :-
@@ -542,7 +572,7 @@ connect_ugraph(Graph, Start, [Start-Vertices|Graph]) :-
% Unify Before to a term that comes before Term in the standard
% order of terms.
%
% Throws instantiation_error if Term is unbound.
% Throws `instantiation_error` if Term is unbound.
before(X, _) :-
var(X),
@@ -561,12 +591,13 @@ before(_, 0).
% _not_ connected in UGraphIn and all edges from UGraphIn removed.
% Example:
%
% ?- complement([1-[3,5],2-[4],3-[],
% 4-[1,2,7,5],5-[],6-[],7-[],8-[]], NL).
% NL = [1-[2,4,6,7,8],2-[1,3,5,6,7,8],3-[1,2,4,5,6,7,8],
% 4-[3,5,6,8],5-[1,2,3,4,6,7,8],6-[1,2,3,4,5,7,8],
% 7-[1,2,3,4,5,6,8],8-[1,2,3,4,5,6,7]]
%
% ```
% ?- complement([1-[3,5],2-[4],3-[],
% 4-[1,2,7,5],5-[],6-[],7-[],8-[]], NL).
% NL = [1-[2,4,6,7,8],2-[1,3,5,6,7,8],3-[1,2,4,5,6,7,8],
% 4-[3,5,6,8],5-[1,2,3,4,6,7,8],6-[1,2,3,4,5,7,8],
% 7-[1,2,3,4,5,6,8],8-[1,2,3,4,5,6,7]]
% ```
% TODO: Simple two-step algorithm. You could be smarter, I suppose.
@@ -586,8 +617,10 @@ complement([V-Ns|G], Vs, [V-INs|NG]) :-
% True when Vertices is an ordered set of vertices reachable in
% UGraph, including Vertex. Example:
%
% ?- reachable(1,[1-[3,5],2-[4],3-[],4-[5],5-[]],V).
% V = [1, 3, 5]
% ```
% ?- reachable(1,[1-[3,5],2-[4],3-[],4-[5],5-[]],V).
% V = [1, 3, 5]
% ```
reachable(N, G, Rs) :-
reachable([N], G, [N], Rs).