The theory of Riemann surfaces has a geometric and an analytic part. The former deals with the axiomatic definition of a Riemann surface, methods of. Riemann Surfaces. Front Cover. Lars V. Ahlfors, Leo Sario. Princeton University Press, Jan 1, – Mathematics – pages. A detailed exposition, and proofs, can be found in Ahlfors-Sario [], Forster Riemann Surface Meromorphic Function Elliptic Curve Complex Manifold.

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A topology 9″ 1 is said to be weaker than the topology r 2 if r 1 c r ‘1.

### Riemann Surfaces – Lars V. Ahlfors, Leo Sario – Google Books

The section can of course be o. On the other hand, it is much easier to obtain superficial knowledge without use of triangulations, for instance, by the method of singular homology.

This maximal connected set is called the romJmnPnl of the “l”H’I’ dt’l’l’llined hy the point. Sometimes it is more convenient to express compactneea in terms of closed seta. This means that points can be identified which were not initially in the same space. As a consequence of 3B every point in a topological space belongs to a maximal connected subset, namely the union of all connected sets which contnin the given point.

Certain characteristic properties which may or may not be present in a topological space are very important not only in the’ general theory, but in particular for the study of surfaces. C C X Xcomo This definition has an obvious generalization to the case of an arbi- trary collection of topological spaces. An open set is a neighborhood of any subset, and a set is open if it contains a neighborhood of every point in the set. It so happens that this superficial knowledge is adequate for most applications to the theory of Riemann surfaces, and our presentation is influenced by this fact.

The complement of an open set is said to be cloftd. If there arc no relations between the points, pure set theory exhausts all poRsibilities. A apace with more than one point can be topologized in different manners. This is done by formulating the combinatorial theory as a theory of triangulated surfaces, or polyhedrons. In most a third requirement is added: This reasoning applies equally well to Oz, and we find that 01 and 02 cannot both be nonempty and at the same time disjoint.

B The intersection of any finite collldion of sets in fJI is a union of sets in We proceed to the definition of compact spaces. Rn is also locally connected. It is therefore convenient to introduce the notion of a basis for the open sets briefly: The compomntB of a locally connuted space are Bimtdtamously open and cloBed.

Surface acetylation of bacterial cellulose Surface acetylation of bacterial cellulose. The definition applies also to subsets in their relative topology, and we can hence apeak of connected and disconnected subsets. The empty set and all seta with only one point are trivially con- nected. In other words, p belongs to the boundary of P if and only if every V p interaecta Pas well as the complement of P.

If thiH is so, one of the seta must be empty, and we conclude that the property holds for all points or for no points. But 01 is also relatively closed in Q. This elementary section has been included for the sakP of l”ompleteness and because beginning analysts are not always well prepared on this point.

If 01 is not empty it meets at least one P.

In most a third requirement is added:. From the connectedness of P. An open covering of a subset is then a family of open seta whose union contains the given subset, and if the subset is compact we can again select a finite aubcovering. The following conditions shall be fulfilled:. A Migllborlwod of a set A c 8 is a set V c 8 which.

### Springer : Review: Lars V. Ahlfors and Leo Sario, Riemann surfaces

Surface nano-architecture of a metalorganic framework Surface nano-architecture of a metalorganic framework. We shall always understand that the topology on a subset is its relative topology. The chapter closes ahlforw the construction of a triangulation. In other instances the analytical method becomes so involved that it no longer possesses the merit of elegance.

The main demerit of this approach is that it does not yield complete results. We ssrio this topology on S’ the relative topology induced by the topology on B. Condition B is a consequence of 1 the triangle inequality, and Rtt is a Hausdorff apace. One of these is the process of relativization. Every open subset of a locally connected space is itself locally connected, for it has a basis conaisting of part of the basis for the whole space. They are relatively open with surfacees to P.

## Lars V. Ahlfors, L. Sario – Riemann Surfaces

The following conditions shall be fulfilled: The following theorem is thus merely a rephrasing of the definition. A space iB compact if and only if every open covering contains a finite BUbcovering. This is the moat useful form of the definition for a whole category of proofs. It must be observed, however, that the new space is not necessarily a Hausdorff space even if Sis one.

Mii1Nr of which ia tloitl.