Monday, 5 January 2015

Linguistic Premise Premise of Algebraic Linguistics 4-1 / September 29, 2007

Linguistic Premise

 Premise of Algebraic Linguistics 4-1

    TANAKA Akio

1 <presheaf>
Topological space     X
Open set of X     U
Abelian group     F ( )     assumption F ( 0 ) = { 0 }
Element of F ( )     Section in F over U
Map between sets     U  
Restriction map      Homomorphism  rUU F  F (   F ( )     assumption rUU F  = id  F (  and  rUU ◯ rU’U’ ‘= rUU’’
Presheaf is contrafunctor from category of open set over X to category of abelian group.
Contrafunctor and category are the terms of category theory. The definitions are omitted now.

2 <sheaf>
Topological space     X
Open set of X     U
Union among finite or infinite open sets     U = λΛUλ
Uλμ := UλUμ
F ( ) = Ker [ ПλμΛ : ПλΛF ( Uλ → ПλμΛF ( Uλμ ) ]
Ker is kernel. Refer to
The upper formula expressed function’s globalization and localized functions’ putted globalized situation.

3 <structure sheaf>
Topological space     X
Open set of X     U
Topological manifold     M
Real number valued continuous functions over U     ГUO M )
O  is structure sheaf that defines geometric structure. One of the generalized structures is scheme.

4 <stalk and germ>
Topological space     X
Open set of X     U
Abelian group     F ( )     assumption F ( 0 ) = { 0 }
Point     P  X
Neighborhood of the point     { P  U }
Stalk of presheaf at  P      direct limit Fp = lim P  U F ( )
Element of stalk Fp      Germ of presheaf at P     

5 <homomorphism of presheaf>
Presheaf     F ,  G
Open set     U
Homomorphism f ( U ) : F (  G ( )    
assumption  rUU F  F (   F ( )    F (  rUU F  =  rUU G    F (  )
F ( U ) is subsheaf of G , when ) is surjection of subset.

6 <kernel of sheaf>
Sheaf     F ,  G
Open set     U
Homomorphism f ( U ) : F (  G ( )
K is subsheaf of F , when K ( ) = Ker ( f ( U ) ) .
K is kernel ,expressed by Ker ( ).

7 <quotient sheaf>
Presheaf     ⊂ F
Quotient sheaf F / G  is  associated from presheaf F ( U ) / U ).

Tokyo September 29, 2007
Sekinan Research Field of Language

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