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@@ -184,7 +184,14 @@ van Heijenoort (ed) 1967 *From Frege to Goedel,
 Cresswell has also developed a variable-free approach of some philosophical and linguistic interest
 in two books in the 1990's.
 
 Cresswell has also developed a variable-free approach of some philosophical and linguistic interest
 in two books in the 1990's.
 

-These systems are Turing complete. In other words: every computation we know how to describe can be represented in a logical system consisting of only a single primitive operation!
+A final linguistic application: Steedman's Combinatory Categorial Grammar, where the "Combinatory" is 
+from combinatory logic (see especially his 2000 book, *The Syntactic Process*).  Steedman attempts to build
+a syntax/semantics interface using a small number of combinators, including T = \xy.yx, B = \fxy.f(xy),
+and our friend S.  Steedman used Smullyan's fanciful bird 
+names for the combinators, Thrush, Bluebird, and Starling.
+
+Many of these combinatory logics, in particular, the SKI system, 
+are Turing complete. In other words: every computation we know how to describe can be represented in a logical system consisting of only a single primitive operation!

 
 Here's more to read about combinatorial logic.
 Surely the most entertaining exposition is Smullyan's [[!wikipedia To_Mock_a_Mockingbird]].
 
 Here's more to read about combinatorial logic.
 Surely the most entertaining exposition is Smullyan's [[!wikipedia To_Mock_a_Mockingbird]].