From d60e2a736b3a227351f4d02b47d695ec3eaad79f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20L=C3=BChne?= <patrick@luehne.de>
Date: Sun, 22 Apr 2018 22:26:17 +0200
Subject: [PATCH] Update examples
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This updates the examples to showcase the scope of anthem’s feature set.
New examples are added concerning placeholders, hiding predicates, and
simplifications related to integer variables.
---
 examples/choice-rules.lp         |  2 ++
 examples/graph-coloring.lp       | 20 ++++++++++++++------
 examples/letters.lp              | 11 +++++++++++
 examples/permutations.lp         |  4 ++--
 examples/schur-numbers.lp        |  4 ++--
 examples/simple-external-show.lp |  9 +++++++++
 examples/simple-external.lp      |  5 +++++
 7 files changed, 45 insertions(+), 10 deletions(-)
 create mode 100644 examples/choice-rules.lp
 create mode 100644 examples/letters.lp
 create mode 100644 examples/simple-external-show.lp
 create mode 100644 examples/simple-external.lp

diff --git a/examples/choice-rules.lp b/examples/choice-rules.lp
new file mode 100644
index 0000000..7cba339
--- /dev/null
+++ b/examples/choice-rules.lp
@@ -0,0 +1,2 @@
+p(a).
+{q(a)}.
diff --git a/examples/graph-coloring.lp b/examples/graph-coloring.lp
index 53fef3b..670e8b5 100644
--- a/examples/graph-coloring.lp
+++ b/examples/graph-coloring.lp
@@ -1,10 +1,18 @@
-#external color(1).
-#external edge(2).
-#external vertex(1).
-#show color/2.
-
+% assign a set of colors to each vertex
 {color(V, C)} :- vertex(V), color(C).
+
+% at most one color per vertex
+:- color(V, C1), color(V, C2), C1 != C2.
+
+% at least one color per vertex
 covered(V) :- color(V, _).
 :- vertex(V), not covered(V).
+
+% adjacent vertices don’t share the same color
 :- color(V1, C), color(V2, C), edge(V1, V2).
-:- color(V, C1), color(V, C2), C1 != C2.
+
+#show color/2.
+
+#external vertex(1).
+#external edge(2).
+#external color(1).
diff --git a/examples/letters.lp b/examples/letters.lp
new file mode 100644
index 0000000..6dc4e14
--- /dev/null
+++ b/examples/letters.lp
@@ -0,0 +1,11 @@
+letter(a).
+letter(b).
+letter(c).
+
+{p(1..3, Y)} :- letter(Y).
+:- p(X1, Y), p(X2, Y), X1 != X2.
+
+q(X) :- p(X, _).
+:- X = 1..3, not q(X).
+
+#show p/2.
diff --git a/examples/permutations.lp b/examples/permutations.lp
index 844d6e0..ac911b4 100644
--- a/examples/permutations.lp
+++ b/examples/permutations.lp
@@ -1,3 +1,5 @@
+#show p/2.
+
 {p(1..n, 1..n)}.
 
 :- p(X, Y1), p(X, Y2), Y1 != Y2.
@@ -8,5 +10,3 @@ q2(Y) :- p(_, Y).
 
 :- not q1(X), X = 1..n.
 :- not q2(Y), Y = 1..n.
-
-#show p/2.
diff --git a/examples/schur-numbers.lp b/examples/schur-numbers.lp
index cdbbca9..5c4e63a 100644
--- a/examples/schur-numbers.lp
+++ b/examples/schur-numbers.lp
@@ -1,7 +1,7 @@
+#show in/2.
+
 {in(1..n, 1..r)}.
 covered(I) :- in(I, S).
 
 :- I = 1..n, not covered(I).
 :- in(I, S), in(J, S), in(I + J, S).
-
-#show in/2.
diff --git a/examples/simple-external-show.lp b/examples/simple-external-show.lp
new file mode 100644
index 0000000..3739bb2
--- /dev/null
+++ b/examples/simple-external-show.lp
@@ -0,0 +1,9 @@
+s(X) :- p(X).
+s(X) :- q(X).
+u(X) :- r(X), not s(X).
+
+#show u/1.
+
+#external p(1).
+#external q(1).
+#external r(1).
diff --git a/examples/simple-external.lp b/examples/simple-external.lp
new file mode 100644
index 0000000..ed9a3dd
--- /dev/null
+++ b/examples/simple-external.lp
@@ -0,0 +1,5 @@
+s(X) :- p(X).
+s(X) :- q(X).
+
+#external p(1).
+#external q(1).