Geometria e Algebra -...
Transcript of Geometria e Algebra -...
Geometria e Algebra
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I gruppi di Geometria e di Algebra
Geometria
Gian Pietro Pirola
Francesco Bonsante
Paola Frediani
Alessandro Ghigi
Ludovico Pernazza
??
Algebra
Alberto Canonaco
I corsi
Istituzioni di Algebra.
Algebra superiore.
Istituzioni di Geometria.
Geometria superiore.
Curve algebriche e superfici di Riemann.
I corsi
Istituzioni di Algebra.
Algebra superiore.
Istituzioni di Geometria.
Geometria superiore.
Curve algebriche e superfici di Riemann.
I corsi
Istituzioni di Algebra.
Algebra superiore.
Istituzioni di Geometria.
Geometria superiore.
Curve algebriche e superfici di Riemann.
I corsi
Istituzioni di Algebra.
Algebra superiore.
Istituzioni di Geometria.
Geometria superiore.
Curve algebriche e superfici di Riemann.
I corsi
Istituzioni di Algebra.
Algebra superiore.
Istituzioni di Geometria.
Geometria superiore.
Curve algebriche e superfici di Riemann.
I corsi
Istituzioni di Algebra.
Algebra superiore.
Istituzioni di Geometria.
Geometria superiore.
Curve algebriche e superfici di Riemann.
Programma di Istituzioni di Algebra
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.2 Localizzazione di anelli e di moduli.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.2 Localizzazione di anelli e di moduli.3 Anelli e moduli artiniani e noetheriani.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.2 Localizzazione di anelli e di moduli.3 Anelli e moduli artiniani e noetheriani.4 Dimensione di Krull di un anello.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.2 Localizzazione di anelli e di moduli.3 Anelli e moduli artiniani e noetheriani.4 Dimensione di Krull di un anello.5 Dipendenza integrale.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.2 Localizzazione di anelli e di moduli.3 Anelli e moduli artiniani e noetheriani.4 Dimensione di Krull di un anello.5 Dipendenza integrale.6 Spettro di un anello; insiemi algebrici affini.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Algebra commutativa (3 crediti, Alberto Canonaco).1 Moduli su un anello commutativo.2 Localizzazione di anelli e di moduli.3 Anelli e moduli artiniani e noetheriani.4 Dimensione di Krull di un anello.5 Dipendenza integrale.6 Spettro di un anello; insiemi algebrici affini.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).1 Numeri algebrici. Interi Algebrici, Campi di Numeri.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.3 Rappresentazione geometrica dei numeri algebrici.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.3 Rappresentazione geometrica dei numeri algebrici.4 Teorema delle unita di Dirichlet.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.3 Rappresentazione geometrica dei numeri algebrici.4 Teorema delle unita di Dirichlet.5 Teoria di Galois per campi di numeri.
Programma di Istituzioni di Algebra
Docenti: Alberto Canonaco, Gian Pietro Pirola.
Teoria dei numeri (6 crediti, Gian Pietro Pirola).1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.3 Rappresentazione geometrica dei numeri algebrici.4 Teorema delle unita di Dirichlet.5 Teoria di Galois per campi di numeri.
Programma di Istituzioni di Algebra
Docente: Gian Pietro Pirola.
Teoria dei numeri.1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.3 Rappresentazione geometrica dei numeri algebrici.4 Teorema delle unita di Dirichlet.5 Teoria di Galois per campi di numeri.6 Introduzione alla teoria di Minkowski e al teorema di Riemann Roch.
Programma di Algebra superiore
Docente: Gian Pietro Pirola.
Teoria dei numeri.1 Numeri algebrici. Interi Algebrici, Campi di Numeri.2 Anelli di Dedekind. Gruppo delle classi.3 Rappresentazione geometrica dei numeri algebrici.4 Teorema delle unita di Dirichlet.5 Teoria di Galois per campi di numeri.6 Introduzione alla teoria di Minkowski e al teorema di Riemann Roch.
Istituzioni di Algebra / Algebra superiore
L’anno prossimo:
Istituzioni di Algebra / Algebra superiore
L’anno prossimo:
1 Prima parte: probabilmente uguale (??).
Istituzioni di Algebra / Algebra superiore
L’anno prossimo:
1 Prima parte: probabilmente uguale (??).
2 Seconda parte:geometria algebrica??algebre di Lie??rappresentazioni di gruppi??
Programma di Istituzioni di Geometria
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Prima parte (3 crediti).Introduzione alle varieta differenziabili.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Prima parte (3 crediti).Introduzione alle varieta differenziabili.
1 Varieta differenziabili. Spazio tangente e cotangente. Sottovarieta.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Prima parte (3 crediti).Introduzione alle varieta differenziabili.
1 Varieta differenziabili. Spazio tangente e cotangente. Sottovarieta.2 Campi vettoriali. Forme differenziali.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Prima parte (3 crediti).Introduzione alle varieta differenziabili.
1 Varieta differenziabili. Spazio tangente e cotangente. Sottovarieta.2 Campi vettoriali. Forme differenziali.3 Elementi di topologia differenziale:
lemma di Sard, formula di Stokes, coomologia di de Rham.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Seconda parte (6 crediti).Topologia delle varieta e dei fibrati vettoriali.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Seconda parte (6 crediti).Topologia delle varieta e dei fibrati vettoriali.
1 Dualita di Poincare. Sottovarieta e dualita.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Seconda parte (6 crediti).Topologia delle varieta e dei fibrati vettoriali.
1 Dualita di Poincare. Sottovarieta e dualita.2 Fibrati. Fibrati vettoriali reali e complessi.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Seconda parte (6 crediti).Topologia delle varieta e dei fibrati vettoriali.
1 Dualita di Poincare. Sottovarieta e dualita.2 Fibrati. Fibrati vettoriali reali e complessi.3 Intorno tubolari e dualita. Classe di Eulero.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Seconda parte (6 crediti).Topologia delle varieta e dei fibrati vettoriali.
1 Dualita di Poincare. Sottovarieta e dualita.2 Fibrati. Fibrati vettoriali reali e complessi.3 Intorno tubolari e dualita. Classe di Eulero.4 Teoria dei fasci. Coomologia di Cech. Fasci localmente costanti e
fibrati piatti.
Programma di Istituzioni di Geometria
Docente: Francesco Bonsante.
Seconda parte (6 crediti).Topologia delle varieta e dei fibrati vettoriali.
1 Dualita di Poincare. Sottovarieta e dualita.2 Fibrati. Fibrati vettoriali reali e complessi.3 Intorno tubolari e dualita. Classe di Eulero.4 Teoria dei fasci. Coomologia di Cech. Fasci localmente costanti e
fibrati piatti.5 Classi di Chern e di Pontrjagin. Classificazione dei fibrati vettoriali
complessi. Connessioni, curvatura e classi caratteristiche.
Programma di Geometria superiore
Docente: Francesco Bonsante.
1 Dualita di Poincare. Sottovarieta e dualita.2 Fibrati. Fibrati vettoriali reali e complessi.3 Intorno tubolari e dualita. Classe di Eulero.4 Teoria dei fasci. Coomologia di Cech. Fasci localmente costanti e
fibrati piatti.5 Classi di Chern e di Pontrjagin. Classificazione dei fibrati vettoriali
complessi. Connessioni, curvatura e classi caratteristiche.
Istituzioni di Geometria / Geometria superiore
L’anno prossimo:
Istituzioni di Geometria / Geometria superiore
L’anno prossimo:
1 Prima parte: probabilmente uguale (??).
Istituzioni di Geometria / Geometria superiore
L’anno prossimo:
1 Prima parte: probabilmente uguale (??).
2 Seconda parte: probabilmente geometria Riemanniana (??).
Programma di Curve algebriche e superfici di Riemann
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Divisori e funzioni meromorfe.
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Divisori e funzioni meromorfe.
Fasci e coomologia. Fibrati vettoriali olomorfi.
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Divisori e funzioni meromorfe.
Fasci e coomologia. Fibrati vettoriali olomorfi.
Forme differenziali olomorfe e meromorfe.
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Divisori e funzioni meromorfe.
Fasci e coomologia. Fibrati vettoriali olomorfi.
Forme differenziali olomorfe e meromorfe.
Teorema di Riemann-Roch.
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Divisori e funzioni meromorfe.
Fasci e coomologia. Fibrati vettoriali olomorfi.
Forme differenziali olomorfe e meromorfe.
Teorema di Riemann-Roch.
La Jacobiana di una curva.
Programma di Curve algebriche e superfici di Riemann
Docente: ??
Superfici di Riemann. Curve algebriche.
Divisori e funzioni meromorfe.
Fasci e coomologia. Fibrati vettoriali olomorfi.
Forme differenziali olomorfe e meromorfe.
Teorema di Riemann-Roch.
La Jacobiana di una curva.
Teorema di Abel.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Curve algebriche e spazio dei moduli.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Curve algebriche e spazio dei moduli.
Costruzione di famiglie di curve interessanti.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Curve algebriche e spazio dei moduli.
Costruzione di famiglie di curve interessanti.
Rette in Cn+1 Pn(C).
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Curve algebriche e spazio dei moduli.
Costruzione di famiglie di curve interessanti.
Rette in Cn+1 Pn(C).
Tutte le curve di genere g Mg .
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Curve algebriche e spazio dei moduli.
Costruzione di famiglie di curve interessanti.
Rette in Cn+1 Pn(C).
Tutte le curve di genere g Mg .
Mg :={curve di genere g}
isomorfismo
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Hodge e applicazione dei periodi.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Hodge e applicazione dei periodi.118 6 Riemann Surfaces
Fig. 6.1 Genus-2 surface.
There is another standard model for these surfaces [99] that is also quite useful(for instance for computing the fundamental group). A genus-g surface can be con-structed by gluing the sides of a 2g-gon. It is probably easier to visualize this inreverse. After cutting the genus-2 surface of Figure 6.1 along the indicated curves,it can be opened up to an octagon (see Figure 6.2).
Fig. 6.2 Genus-2 surface cut open.
The topological Euler characteristic of the space X is
e(X) =∑(−1)i dim Hi(X ,R).
From Exercise 4.5.5, we have the following lemma:
Lemma 6.1.2. If X is a union of two open sets U and V , then e(X) = e(U)+e(V)−e(U ∩V ).
Corollary 6.1.3. If X is a manifold of genus g, then e(X) = 2−2g, and the first Bettinumber is given by dimH1(X ,R) = 2g.
Proof. This will be left for the exercises. When g = 2, this gives dimH1(X ,R) = 4. We can find explicit generators by
taking the fundamental classes of the curves a1,a2,b1,b2 in Figure 6.1, after choos-ing orientations. To see that these generate, H1(X ,R), it suffices to prove that theyare linearly independent. For this, consider the pairing
(α,β ) �→∫
Xα ∧β
∫aj
ωk = δjk , Bjk :=
∫bj
ωk ,
B = BT , ImB > 0.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Superfici algebriche: classificazione, fibrazioni, topologia.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Superfici algebriche: classificazione, fibrazioni, topologia.
Una superficie K3.
1 + x4 + y4 + z4 + a(x2 + y2 + z2 + 1)2 = 0, a = −0.49
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Galois geometrica.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Galois geometrica.
X :=
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Galois geometrica.
X :=
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
= 2×
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Galois geometrica.
X :=
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
= 2×
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
f : X2:1−−−→ S2 = P1(C),
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Galois geometrica.
X :=
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
= 2×
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
f : X2:1−−−→ S2 = P1(C), C(z) ⊂ C(X ) := {funzioni meromorfe su X}
RicercaGeometria algebrica e complessa (Pirola, Frediani, Ghigi)
Teoria di Galois geometrica.
X :=
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
1.1. Riemann Surfaces 5
Fig. 1.4.
Fig. 1.5.
1.1.3. Closed Riemann Surfaces
A Riemann surface homeomorphic to a sphere with 9 handles as in Fig. 1.6 is called a closed Riemann surface of genus g. The Riemann sphere is of genus 0, and a torus is of genus 1. It is well-known that every compact Riemann surface is a closed Riemann surface of finite genus. A non-compact Riemann surface is called an open Riemann surface.
Take a point Po on a closed Riemann surface R of genus 9 and cut R along simple closed curves AI, Bl, ... , Ag, Bg with base point Po as in Fig. 1.6. Then we get a domain homeomorphic to a convex polygon with 4g sides (Fig. 1.7).
The fundamental group 'lT1 (R, Po) of R with base point Po is generated by the homotopy classes [AI], [BI l, ... , [Ag], [Bg] induced from AI, B I , ... , Ag, Bg and satisfies the fundamental relation
9
II[Aj][Bj][Aj]-I[Bj]-1 = 1 (the unit). j=l
We call {[Ajl,[Bj]H=1 or {Aj,Bj H=l a canonical system of generators of 'lT1(R,po).
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
= 2×
4 1. Teichmiiller Space of Genus 9
mapping. This R is the Riemann surface of w = vz. (See Ahlfors [A-4J, Chap. 8; Jones and Singerman [A-48], Chap. 4; and Springer [A-99], Chap. 1.)
Note that the Riemann surface R of the algebraic function w = vz is also regarded as the algebraic curve defined by the equation w2 = z.
Finally, we see elliptic curves, i.e., tori from the viewpoint of algebraic curves. For any complex number >.(f. 0,1), let R be the algebraic curve defined by the equation
w 2 = z(z - l)(z - >.). (1.1)
In other words, R consists of all points (z, w) E C x C satisfying algebraic equation (1.1) and the point Poo = (00,00). We can define the complex structure of R by the complex structure of the z-sphere so that the projection 1f': R -+
C, 1f'(z, w) = z, is holomorphic. This R is a two-sheeted branched covering surface over the z-sphere with branch· points 0, 1, >., and 00. The mapping f: R -+ C, f(z, w) = w, is holomorphic. This function f is written as w = Jz(z - 1)(z - >.) and R is a Riemann surface on which the algebraic function w = Jz(z - 1)(z - >.) is single-valued.
The Riemann surface R defined by algebraic equation (1.1) is regarded topologically as a surface illustrated in Fig. 1.5. Take two copies of the Riemann spheres Sl, S2 with cuts between ° and 1, and between>. and 00 (Fig. 1.3). Place them face to face (Fig. 1.4), and join along their cuts (Fig. 1.5). The resulting surface is homeomorphic to the Riemann surface R. Hence, R looks like the surface of a doughnut. We call such a Riemann surface a torus. A torus is also called an elliptic curve; this name comes from the elliptic integral (see §1.4).
00 00
Fig. 1.3.
f : X2:1−−−→ S2 = P1(C), C(z) ⊂ C(X ) := {funzioni meromorfe su X}
Gal (C (X ) /C (z)) .
RicercaAlgebra omologica e teoria delle categorie (Canonaco)
Categorie derivate
RicercaAlgebra omologica e teoria delle categorie (Canonaco)
Categorie derivate
L’assioma dell’ottaedroper le categorietriangolate:
Y ′
g
[1]
��
Z ′
f
>>
[1]
��
X ′j[1]◦i
[1]oo
i[1]
��
Xv◦u //
u
Z
OO
WW
Y
v
>>
j
WW
RicercaGeometria differenziale (Bonsante)
Geometria iperbolica.
Spazi di Teichmuller.Strettamente collegatoallo spazio dei modulidelle curve algebriche, mada un punto di vistadifferenziale.
Fibrati piatti e varieta dirappresentazioni.
Azioni di gruppi su spazisimmetrici.
RicercaGeometria differenziale (Bonsante)
Geometria iperbolica.
Spazi di Teichmuller.Strettamente collegatoallo spazio dei modulidelle curve algebriche, mada un punto di vistadifferenziale.
Fibrati piatti e varieta dirappresentazioni.
Azioni di gruppi su spazisimmetrici.
RicercaGeometria differenziale (Bonsante)
Geometria iperbolica.
Spazi di Teichmuller.Strettamente collegatoallo spazio dei modulidelle curve algebriche, mada un punto di vistadifferenziale.
Fibrati piatti e varieta dirappresentazioni.
Azioni di gruppi su spazisimmetrici.
RicercaGeometria differenziale (Bonsante)
Geometria iperbolica.
Spazi di Teichmuller.Strettamente collegatoallo spazio dei modulidelle curve algebriche, mada un punto di vistadifferenziale.
Fibrati piatti e varieta dirappresentazioni.
Azioni di gruppi su spazisimmetrici.
RicercaGeometria differenziale (Bonsante)
Geometria iperbolica.
Spazi di Teichmuller.Strettamente collegatoallo spazio dei modulidelle curve algebriche, mada un punto di vistadifferenziale.
Fibrati piatti e varieta dirappresentazioni.
Azioni di gruppi su spazisimmetrici.
RicercaGeometria analitica reale (Pernazza)
Geometria analitica reale.
L’ombrello di Whitney: x2 − y2z = 0.
RicercaGeometria analitica reale (Pernazza)
Geometria analitica reale.
L’ombrello di Whitney: x2 − y2z = 0.
RicercaGeometria analitica reale (Pernazza)
Geometria analitica reale.
L’ombrello di Whitney: x2 − y2z = 0.
Tematiche di tesi
In tutti gli argomenti di ricerca appena elencati. E in alcuni altri . . .
Tematiche di tesi
In tutti gli argomenti di ricerca appena elencati. E in alcuni altri . . .
Negli ultimi anni molti studenti si sono laureati a Pavia su argomenti dicarattere algebrico o geometrico. Vari di questi sono entrati al dottorato aPavia o altrove.