# ===========================================================================
# French cities — ARC style graph reachability example.
# Based on https://raw.githubusercontent.com/eyereasoner/eyeling/refs/heads/main/examples/french-cities.n3
#
# This example shows how simple graph rules can answer a practical travel-style
# question: which cities can reach Nantes by following one-way connections?
# The program derives longer paths from shorter ones, explains why the answer is
# correct, and checks the key steps independently.
# ===========================================================================
@prefix log: .
@prefix owl: .
@prefix rdfs: .
@prefix string: .
@prefix : .

# Facts
:paris :oneway :orleans.
:paris :oneway :chartres.
:paris :oneway :amiens.
:orleans :oneway :blois.
:orleans :oneway :bourges.
:blois :oneway :tours.
:chartres :oneway :lemans.
:lemans :oneway :angers.
:lemans :oneway :tours.
:angers :oneway :nantes.
:oneway rdfs:subPropertyOf :path.
:path a owl:TransitiveProperty.
:paris :label "Paris".
:chartres :label "Chartres".
:lemans :label "Le Mans".
:angers :label "Angers".
:nantes :label "Nantes".

# RDFS / OWL rules from the original example
{ ?P rdfs:subPropertyOf ?Q. ?S ?P ?O. } => { ?S ?Q ?O. }.
{ ?P rdfs:subPropertyOf ?Q. ?Q rdfs:subPropertyOf ?R. } => { ?P rdfs:subPropertyOf ?R. }.
{ ?P a owl:TransitiveProperty. ?S ?P ?X. ?X ?P ?O. } => { ?S ?P ?O. }.

# ARC logic
{ ?C :path :nantes. } => { ?C :canReach :nantes. }.
{ :paris :canReach :nantes. } => { :report :reachableCity :paris. }.
{ :chartres :canReach :nantes. } => { :report :reachableCity :chartres. }.
{ :lemans :canReach :nantes. } => { :report :reachableCity :lemans. }.
{ :angers :canReach :nantes. } => { :report :reachableCity :angers. }.
{ :report :reachableCity :paris, :chartres, :lemans, :angers. } => { :report :outcome "Four cities in this small network can reach Nantes: Paris, Chartres, Le Mans, and Angers.". }.

# Independent check facts
{ :angers :oneway :nantes. } => { :check :c1 "OK - Angers has a direct one-way connection to Nantes.". }.
{ :lemans :oneway :angers. :angers :path :nantes. } => { :check :c2 "OK - Le Mans reaches Nantes by chaining Le Mans → Angers → Nantes.". }.
{ :chartres :oneway :lemans. :lemans :path :nantes. } => { :check :c3 "OK - Chartres reaches Nantes by chaining Chartres → Le Mans → Angers → Nantes.". }.
{ :paris :oneway :chartres. :chartres :path :nantes. } => { :check :c4 "OK - Paris reaches Nantes by chaining Paris → Chartres → Le Mans → Angers → Nantes.". }.
{ :orleans :path :nantes. } => false.
{ :amiens :path :nantes. } => false.
{ :bourges :path :nantes. } => false.
{ :blois :path :nantes. :blois log:notEqualTo :nantes. } => false.
{ :tours :path :nantes. :tours log:notEqualTo :nantes. } => false.
{ :report :reachableCity ?C. ?C :label ?L. } => { ?C :reachableLabel ?L. }.

# ARC output
{ :report :outcome ?Outcome.
  :paris :reachableLabel ?Paris.
  :chartres :reachableLabel ?Chartres.
  :lemans :reachableLabel ?LeMans.
  :angers :reachableLabel ?Angers.
  :check :c1 ?C1; :c2 ?C2; :c3 ?C3; :c4 ?C4.
  ( "French cities — ARC style graph reachability\n\n"
    "Answer\n" ?Outcome "\n\n"
    "Reason Why\n"
    "The original example says that every :oneway link is also a :path, and that :path is transitive. "
    "So once Angers can reach Nantes directly, longer routes can be built by chaining earlier links. "
    ?Angers " reaches Nantes directly. "
    ?LeMans " reaches Nantes through Angers. "
    ?Chartres " reaches Nantes through Le Mans and Angers. "
    ?Paris " reaches Nantes through Chartres, Le Mans, and Angers.\n\n"
    "Check\n"
    "C1 " ?C1 "\n"
    "C2 " ?C2 "\n"
    "C3 " ?C3 "\n"
    "C4 " ?C4 "\n"
    "C5 OK - cities without a chain to Nantes are rejected by fail-loud fuse rules.\n"
  ) string:concatenation ?Block.
} => { :report log:outputString ?Block. }.