protocol

weighted_graph_protocol

Protocol for weighted graph predicates, extending the common graph protocol with weighted edge operations.

Availability:

logtalk_load(graphs(loader))

Author: Paulo Moura

Version: 1:0:0

Date: 2026-02-25

Compilation flags:

static

Extends:

public graph_protocol

Remarks:

(none)

Inherited public predicates:

 add_edges/3  add_vertex/3  add_vertices/3  all_pairs_min_paths/2  all_pairs_min_predecessors/2  breadth_first_order/3  delete_edges/3  delete_vertex/3  delete_vertices/3  depth_first_order/3  edges/2  empty/1  has_path/3  is_bipartite/1  is_complete/1  is_sparse/1  max_path/5  min_distances/3  min_path/5  min_predecessors/3  neighbors/3  new/1  new/2  new/3  number_of_edges/2  number_of_vertices/2  path/3  reachable/3  vertices/2

Public predicates

edge/4

True iff there is an edge between Vertex1 and Vertex2 with weight Weight in Graph.

Compilation flags:

static

Template:

edge(Vertex1,Vertex2,Weight,Graph)

Mode and number of proofs:

edge(+vertex,+vertex,?number,+graph) - zero_or_one

---

add_edge/5

Adds a weighted edge between Vertex1 and Vertex2 with weight Weight.

Compilation flags:

static

Template:

add_edge(Graph,Vertex1,Vertex2,Weight,NewGraph)

Mode and number of proofs:

add_edge(+graph,+vertex,+vertex,+number,-graph) - one

---

delete_edge/5

Deletes the weighted edge between Vertex1 and Vertex2. Unifies Weight with the weight of the deleted edge. The graph is unchanged if the edge does not exist.

Compilation flags:

static

Template:

delete_edge(Graph,Vertex1,Vertex2,Weight,NewGraph)

Mode and number of proofs:

delete_edge(+graph,+vertex,+vertex,?number,-graph) - one

---

wneighbors/3

Unifies WNeighbors with a list of NeighborVertex-Weight pairs for the neighbors of Vertex. Fails if Vertex is not in the graph.

Compilation flags:

static

Template:

wneighbors(Vertex,Graph,WNeighbors)

Mode and number of proofs:

wneighbors(+vertex,+graph,-list(pair)) - zero_or_one

---

min_path_bellman_ford/5

Finds the minimum cost path from Vertex1 to Vertex2 using the Bellman-Ford algorithm. Supports negative edge weights and fails if no path exists or if a reachable negative cycle makes the optimum undefined.

Compilation flags:

static

Template:

min_path_bellman_ford(Vertex1,Vertex2,Graph,Path,Cost)

Mode and number of proofs:

min_path_bellman_ford(+vertex,+vertex,+graph,-list(vertex),-number) - zero_or_one

---

has_negative_cycle/1

True iff Graph contains a negative-weight cycle.

Compilation flags:

static

Template:

has_negative_cycle(Graph)

Mode and number of proofs:

has_negative_cycle(+graph) - zero_or_one

---

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

(no local declarations; see entity ancestors if any)

Operators

(none)