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agdaproofs/Groups/LectureNotes/Lecture1.agda
2019-10-02 18:59:46 +01:00

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{-# OPTIONS --safe --warning=error #-}
open import LogicalFormulae
open import Setoids.Setoids
open import Functions
open import Agda.Primitive using (Level; lzero; lsuc; _⊔_)
open import Numbers.Naturals.Naturals
open import Numbers.Integers.Integers
open import Numbers.Rationals
open import Sets.FinSet
open import Groups.Definition
open import Groups.Groups
open import Rings.Definition
open import Numbers.Modulo.IntegersModN
open import Semirings.Definition
module Groups.LectureNotes.Lecture1 where
IsGroup : _
IsGroup = Group
IsGroup : _
IsGroup = Ring.additiveGroup Ring
-- TODO: R is a group with +
integersMinusNotGroup : Group (reflSetoid ) (_-Z_) False
integersMinusNotGroup record { wellDefined = wellDefined ; identity = identity ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } with multAssoc {nonneg 3} {nonneg 2} {nonneg 1}
integersMinusNotGroup record { wellDefined = wellDefined ; identity = identity ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } | ()
negSuccInjective : {a b : } (negSucc a negSucc b) a b
negSuccInjective {a} {.a} refl = refl
nonnegInjective : {a b : } (nonneg a nonneg b) a b
nonnegInjective {a} {.a} refl = refl
integersTimesNotGroup : Group (reflSetoid ) (_*Z_) False
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (nonneg zero) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } with multIdentLeft {negSucc 1}
... | ()
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (nonneg (succ zero)) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } with invLeft {nonneg zero}
... | bl with inverse (nonneg zero)
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (nonneg (succ zero)) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } | () | nonneg zero
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (nonneg (succ zero)) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } | p | nonneg (succ x) = naughtE (nonnegInjective (transitivity (applyEquality nonneg (equalityCommutative (Semiring.productZeroRight Semiring x))) p))
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (nonneg (succ zero)) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } | () | negSucc x
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (nonneg (succ (succ x))) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } with succInjective (negSuccInjective (multIdentLeft {negSucc 1}))
... | ()
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (negSucc x) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } with multIdentLeft {nonneg 2}
integersTimesNotGroup record { wellDefined = wellDefined ; identity = (negSucc x) ; inverse = inverse ; multAssoc = multAssoc ; multIdentRight = multIdentRight ; multIdentLeft = multIdentLeft ; invLeft = invLeft ; invRight = invRight } | ()
-- TODO: Q is not a group with *Q
-- TODO: Q without 0 is a group with *Q
-- TODO: {1, -1} is a group with *
nIsGroup : (n : ) (0<n : 0 <N n) _
nIsGroup n pr = nGroup n pr
-- Groups example 8.9 from lecture 1
data Weird : Set where
e : Weird
a : Weird
b : Weird
c : Weird
_+W_ : Weird Weird Weird
e +W t = t
a +W e = a
a +W a = e
a +W b = c
a +W c = b
b +W e = b
b +W a = c
b +W b = e
b +W c = a
c +W e = c
c +W a = b
c +W b = a
c +W c = e
+WAssoc : {x y z : Weird} (x +W (y +W z)) (x +W y) +W z
+WAssoc {e} {y} {z} = refl
+WAssoc {a} {e} {z} = refl
+WAssoc {a} {a} {e} = refl
+WAssoc {a} {a} {a} = refl
+WAssoc {a} {a} {b} = refl
+WAssoc {a} {a} {c} = refl
+WAssoc {a} {b} {e} = refl
+WAssoc {a} {b} {a} = refl
+WAssoc {a} {b} {b} = refl
+WAssoc {a} {b} {c} = refl
+WAssoc {a} {c} {e} = refl
+WAssoc {a} {c} {a} = refl
+WAssoc {a} {c} {b} = refl
+WAssoc {a} {c} {c} = refl
+WAssoc {b} {e} {z} = refl
+WAssoc {b} {a} {e} = refl
+WAssoc {b} {a} {a} = refl
+WAssoc {b} {a} {b} = refl
+WAssoc {b} {a} {c} = refl
+WAssoc {b} {b} {e} = refl
+WAssoc {b} {b} {a} = refl
+WAssoc {b} {b} {b} = refl
+WAssoc {b} {b} {c} = refl
+WAssoc {b} {c} {e} = refl
+WAssoc {b} {c} {a} = refl
+WAssoc {b} {c} {b} = refl
+WAssoc {b} {c} {c} = refl
+WAssoc {c} {e} {z} = refl
+WAssoc {c} {a} {e} = refl
+WAssoc {c} {a} {a} = refl
+WAssoc {c} {a} {b} = refl
+WAssoc {c} {a} {c} = refl
+WAssoc {c} {b} {e} = refl
+WAssoc {c} {b} {a} = refl
+WAssoc {c} {b} {b} = refl
+WAssoc {c} {b} {c} = refl
+WAssoc {c} {c} {e} = refl
+WAssoc {c} {c} {a} = refl
+WAssoc {c} {c} {b} = refl
+WAssoc {c} {c} {c} = refl
weirdGroup : Group (reflSetoid Weird) _+W_
Group.wellDefined weirdGroup = reflGroupWellDefined
Group.identity weirdGroup = e
Group.inverse weirdGroup t = t
Group.multAssoc weirdGroup {r} {s} {t} = +WAssoc {r} {s} {t}
Group.multIdentRight weirdGroup {e} = refl
Group.multIdentRight weirdGroup {a} = refl
Group.multIdentRight weirdGroup {b} = refl
Group.multIdentRight weirdGroup {c} = refl
Group.multIdentLeft weirdGroup {e} = refl
Group.multIdentLeft weirdGroup {a} = refl
Group.multIdentLeft weirdGroup {b} = refl
Group.multIdentLeft weirdGroup {c} = refl
Group.invLeft weirdGroup {e} = refl
Group.invLeft weirdGroup {a} = refl
Group.invLeft weirdGroup {b} = refl
Group.invLeft weirdGroup {c} = refl
Group.invRight weirdGroup {e} = refl
Group.invRight weirdGroup {a} = refl
Group.invRight weirdGroup {b} = refl
Group.invRight weirdGroup {c} = refl
weirdAb : AbelianGroup weirdGroup
AbelianGroup.commutative weirdAb {e} {e} = refl
AbelianGroup.commutative weirdAb {e} {a} = refl
AbelianGroup.commutative weirdAb {e} {b} = refl
AbelianGroup.commutative weirdAb {e} {c} = refl
AbelianGroup.commutative weirdAb {a} {e} = refl
AbelianGroup.commutative weirdAb {a} {a} = refl
AbelianGroup.commutative weirdAb {a} {b} = refl
AbelianGroup.commutative weirdAb {a} {c} = refl
AbelianGroup.commutative weirdAb {b} {e} = refl
AbelianGroup.commutative weirdAb {b} {a} = refl
AbelianGroup.commutative weirdAb {b} {b} = refl
AbelianGroup.commutative weirdAb {b} {c} = refl
AbelianGroup.commutative weirdAb {c} {e} = refl
AbelianGroup.commutative weirdAb {c} {a} = refl
AbelianGroup.commutative weirdAb {c} {b} = refl
AbelianGroup.commutative weirdAb {c} {c} = refl
weirdProjection : Weird FinSet 4
weirdProjection a = ofNat 0 (le 3 refl)
weirdProjection b = ofNat 1 (le 2 refl)
weirdProjection c = ofNat 2 (le 1 refl)
weirdProjection e = ofNat 3 (le zero refl)
weirdProjectionSurj : Surjection weirdProjection
Surjection.property weirdProjectionSurj fzero = a , refl
Surjection.property weirdProjectionSurj (fsucc fzero) = b , refl
Surjection.property weirdProjectionSurj (fsucc (fsucc fzero)) = c , refl
Surjection.property weirdProjectionSurj (fsucc (fsucc (fsucc fzero))) = e , refl
Surjection.property weirdProjectionSurj (fsucc (fsucc (fsucc (fsucc ()))))
weirdProjectionInj : (x y : Weird) weirdProjection x weirdProjection y Setoid.__ (reflSetoid Weird) x y
weirdProjectionInj e e fx=fy = refl
weirdProjectionInj e a ()
weirdProjectionInj e b ()
weirdProjectionInj e c ()
weirdProjectionInj a e ()
weirdProjectionInj a a fx=fy = refl
weirdProjectionInj a b ()
weirdProjectionInj a c ()
weirdProjectionInj b e ()
weirdProjectionInj b a ()
weirdProjectionInj b b fx=fy = refl
weirdProjectionInj b c ()
weirdProjectionInj c e ()
weirdProjectionInj c a ()
weirdProjectionInj c b ()
weirdProjectionInj c c fx=fy = refl
weirdFinite : FiniteGroup weirdGroup (FinSet 4)
SetoidToSet.project (FiniteGroup.toSet weirdFinite) = weirdProjection
SetoidToSet.wellDefined (FiniteGroup.toSet weirdFinite) x y = applyEquality weirdProjection
SetoidToSet.surj (FiniteGroup.toSet weirdFinite) = weirdProjectionSurj
SetoidToSet.inj (FiniteGroup.toSet weirdFinite) = weirdProjectionInj
FiniteSet.size (FiniteGroup.finite weirdFinite) = 4
FiniteSet.mapping (FiniteGroup.finite weirdFinite) = id
FiniteSet.bij (FiniteGroup.finite weirdFinite) = idIsBijective
weirdOrder : groupOrder weirdFinite 4
weirdOrder = refl
-- TODO: dihedral groups
-- TODO: matrix groups on R
-- TODO: general linear groups on R