adding good cobbler example

test/pure/cobbler.n3s

@@ -0,0 +1,17 @@
+# Good Cobbler
+# Example from https://shs.hal.science/halshs-04148373/document
+# Using functional logic http://intrologic.stanford.edu/chapters/chapter_11.html
+
+@prefix log: <http://www.w3.org/2000/10/swap/log#>.
+@prefix : <urn:example:>.
+
+# Some x is a good cobbler
+_:x a (:good :Cobbler).
+
+# is there someone x which is good at some y
+(_:x _:y) log:onNegativeSurface {
+    _:x a (:good _:y).
+    () log:onNegativeAnswerSurface {
+        :test :is true.
+    }.
+}.