diff options
| author | Camil Staps | 2016-02-02 19:24:50 +0100 |
|---|---|---|
| committer | Camil Staps | 2016-02-02 19:24:50 +0100 |
| commit | a7d7542dc646a5fd124ef71e71ce260889f1701b (patch) | |
| tree | 04ed89503bbb3cc9933273a1326a53ca724c3492 /fp1/week6/camil/BewijsMapFlatten.icl | |
| parent | week6 camil: working positioning of lines by putting empties at left and righ... (diff) | |
Diffstat (limited to 'fp1/week6/camil/BewijsMapFlatten.icl')
| -rw-r--r-- | fp1/week6/camil/BewijsMapFlatten.icl | 83 |
1 files changed, 0 insertions, 83 deletions
diff --git a/fp1/week6/camil/BewijsMapFlatten.icl b/fp1/week6/camil/BewijsMapFlatten.icl deleted file mode 100644 index 7f2474e..0000000 --- a/fp1/week6/camil/BewijsMapFlatten.icl +++ /dev/null @@ -1,83 +0,0 @@ -// Mart Lubbers, s4109503
-// Camil Staps, s4498062
-
-Zij gegeven:
-
-(++) :: [a] [a] -> [a]
-(++) [] xs = xs (1)
-(++) [y:ys] xs = [y : ys ++ xs] (2)
-
-map :: (a -> b) [a] -> [b]
-map f [] = [] (3)
-map f [x:xs] = [f x : map f xs] (4)
-
-flatten :: [[a]] -> [a]
-flatten [] = [] (5)
-flatten [x:xs] = x ++ (flatten xs) (6)
-
-1.
-Te bewijzen:
- voor iedere functie f, eindige lijst as en bs:
-
- map f (as ++ bs) = (map f as) ++ (map f bs)
-
-Bewijs:
-Met inductie over as.
-
-Inductiebasis:
-Stel as = []. Dan hebben we:
-
- map f (as ++ bs) // aanname as = []
- = map f ([] ++ bs) // definitie van ++, regel 1
- = map f bs // definitie van ++, regel 1
- = [] ++ (map f bs) // definitie van map, regel 3
- = (map f []) ++ (map f bs) // aanname as = []
- = (map f as) ++ (map f bs).
-
-Inductiestap:
-Stel map f (as ++ bs) = (map f as) ++ (map f bs) voor zekere as en elke bs (inductiehypothese). Dan hebben we:
-
- map f ([a:as] ++ bs) // definitie van ++, regel 2
- = map f [a:as ++ bs] // definitie van map, regel 4
- = [f a : map f (as ++ bs)] // inductiehypothese: map f (as ++ bs) = (map f as) ++ (map f bs)
- = [f a : (map f as) ++ (map f bs)] // lijst herschrijven
- = [f a : map f as] ++ (map f bs) // definitie van map, regel 4
- = (map f [a:as]) ++ (map f bs).
-
-Uit het principe van volledige inductie volgt nu dat voor iedere functie f, eindige lijst as en bs:
-
- map f (as ++ bs) = (map f as) ++ (map f bs) (9.4.1)
-
-2.
-Te bewijzen:
- voor iedere functie f, voor iedere eindige lijst xs:
-
- flatten (map (map f) xs) = map f (flatten xs)
-
-Bewijs:
-Met inductie over xs.
-
-Inductiebasis:
-Stel xs = []. Dan hebben we:
-
- flatten (map (map f) xs) // aanname xs = []
- = flatten (map (map f) []) // definitie van map, regel 3
- = flatten [] // definitie van flatten, regel 5
- = [] // definitie van map, regel 3
- = map f [] // definitie van flatten, regel 5
- = map f (flatten []) // aanname xs = []
- = map f (flatten xs).
-
-Inductiestap:
-Stel flatten (map (map f) xs) = map f (flatten xs) voor een zekere eindige lijst xs (inductiehypothese). Dan hebben we:
-
- flatten (map (map f) [x:xs]) // definitie van map, regel 4
- = flatten [map f x : map (map f) xs] // definitie van flatten, regel 6
- = (map f x) ++ flatten (map (map f) xs) // inductiehypothese: flatten (map (map f) xs) = map f (flatten xs)
- = (map f x) ++ (map f (flatten xs)) // 9.4.1
- = map f (x ++ (flatten xs)) // definitie van flatten, regel 6
- = map f (flatten [x:xs]).
-
-Uit het principe van volledige inductie volgt nu dat voor iedere functie f en eindige lijst xs geldt:
-
- flatten (map (map f) xs) = map f (flatten xs)
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