diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+Copyright (c) 2014 gogotanaka
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/Logic.cabal b/Logic.cabal
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--- /dev/null
+++ b/Logic.cabal
@@ -0,0 +1,23 @@
+name:                Logic
+version:             0.1.0.0
+synopsis:            Logic
+-- description:         
+homepage:            http://gogotanaka.me/
+license:             MIT
+license-file:        LICENSE
+author:              gogotanaka
+maintainer:          mail@tanakakazuki.com
+-- copyright:           
+category:            Math
+build-type:          Simple
+extra-source-files:  README.md
+cabal-version:       >=1.10
+
+library
+  exposed-modules:   Logic 
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.7 && <4.8
+  hs-source-dirs:      src
+  default-language:    Haskell2010
+  
diff --git a/README.md b/README.md
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+++ b/README.md
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+# Logic
+
+    :l main.hs
+    p && q
+    p || q
+    p ==> q
+    p <=> q
+    (^) p
diff --git a/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
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+import Distribution.Simple
+main = defaultMain
diff --git a/src/Logic.hs b/src/Logic.hs
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+++ b/src/Logic.hs
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+module Logic where
+
+import Prelude hiding ((^), (&&), (||))
+import Data.List (intercalate)
+data Logic = T | F | Atom String | Neg Logic | Or [Logic] | And [Logic]
+
+instance Show Logic where
+  show x = case x of
+    Atom a -> a
+    Neg p  -> "￢" ++ show p
+    Or ps  -> intercalate " ∨ " (map show ps)
+    And ps -> intercalate " ∧ " (map show ps)
+    T      -> "T"
+    F      -> "F"
+
+p = Atom "p" :: Logic
+q = Atom "q" :: Logic
+r = Atom "r" :: Logic
+
+
+(^) :: Logic -> Logic
+(^) p = Neg p
+
+(||) :: Logic -> Logic -> Logic
+(||) p q = Or [p, q]
+
+(&&) :: Logic -> Logic -> Logic
+(&&) p q = And [p, q]
+
+(==>) :: Logic -> Logic -> Logic
+(==>) p q = (Neg p) ||  q
+
+(<=>) :: Logic -> Logic -> Logic
+(<=>) p q = ((Neg p) || q) && (p || (Neg q))
+