added example for NLG from logical formula. See examples/nlg

examples/nlg/LogicEng.gf

@@ -0,0 +1,23 @@
+--# -path=present
+concrete LogicEng of Logic = open (Eng=GrammarEng), ParadigmsEng, ResEng in {
+
+lincat
+  Ind = {s : Str};
+  Prop = {s:Str};
+
+lin
+  john = {s="john"};
+  mary = {s="mary"};
+  boy x = {s="boy"++"("++x.s++")"};
+  smart x = {s="smart"++"("++x.s++")"};
+  love x y = {s="love"++"("++x.s++","++y.s++")"};
+  leave x = {s="leave"++"("++x.s++")"};
+  and  x y = {s=x.s++"&&"++y.s};
+  or   x y = {s=x.s++"||"++y.s};
+  impl x y = {s=x.s++"=>"++y.s};
+  forall f = {s="forall"++f.$0++"."++"("++f.s++")"};
+  exists f = {s="exists"++f.$0++"."++"("++f.s++")"};
+  not p = {s="not"++"("++p.s++")"};
+  eq x y = {s=x.s++"="++y.s};
+
+}