productive - University of Warwick · Recallltuttheipt compactificationofa locallycompactspace is...
Transcript of productive - University of Warwick · Recallltuttheipt compactificationofa locallycompactspace is...
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Recallltuttheiptcompactificationof alocallycompactspace
isobtainedbyadding a pointand declaring troublegas tree complements
of compactsets
extendotrahomeomorphism
asYt ft
94,4Corusiderlaie
PE i uiY SX Sy a Dist fetto
Csx Sy Cts hormonal
ascompartaetrofecorrespondto
computt syenite 25 0
setsftpse YYP3gIaArwbouuo.soloefous sittin toLs z't
fTwo
game polyhedron inis a topologicalsurfaceconsistingof faces edges
Polyhedralsurface and vertices
Wewill showthat a polyhedrondetermines a Reimannsurface Thisconstructiongives a large number
ofexamples unlikepreviousconstructions includingexamplesof Riemannsurface structures on
oriental surfaces of every genus Theseconstructionseachbuoe a finite ofparametersthat canbe adjusted
Step't We will start byconstructing abortsat interior points of facesOur surface comes with an outward pointingunit normal
Hit Cx4,01a
ePolyhedralsurfaceComtructpolarcoordinatesin a rebel ofp our too 0 0 I 21T
If two points are in theamuefucelton ablecan overlap and transition functions leavethe form 2 a 2 to
ftp.z Coordinates on edgesat a pointp on theboundary
of a facets we
off can construct a
half dials coordinate
If we puttogether apairofthese
Edge points wood we get a dials coordinate4 Decidewhich
Tt halfdishbecomes
theupperhalfJ.fi i aauadwlq.neEe
1 EH
At this point we have an atlasfor P outeciowhereall of the transition unpalumette formQuiz etitttcj.ie This is a holomorphic atlas
of a special form and we will see this again
Steps Coordinates at certain
E
f
anglesmallerthank II HUT 4g
a 4g 2 2 I
IEE a ITEYEDe3Iz
crankshaftconst IutEe
2 Zod saz at o'T
addinginduertaafteriaformgrieuatraisitionfunctions of the form z xEtc where Isisa branch of the powerfunction euddhere
Remark Construction can be applied toa collectionof polyous in LTE with identificationsof sides which need not be realigable in 1123
Parallelogram
I c Identify oppositedi tu sided
In this case the vertex bus cone angled t t r t d t dy IT
Orientationreversingmapsofsides to create orientation
preserving clients
Octagon yo0t t
x sI o
future case all oftheverticesgetidentifiedto a single point and the core angle at that pointis I
There are two typesof pathologicalbehavior tteat can occur
a priori a seafarer need not beHausdorfa surface need not have a countable
base for its topologyRiemann
Here is a simpleexampleofayaurfacewhich is neither Hausdorff was 2ndcountable GiaelRsthetop
it tetpa exy z a Gqditjztpg.im
8ounthequutieitapncecry by identifying exit 7 and
H Y 27 if Yo
C oraruoreaopluoticatedaompkaeeBeeerdou.J
Thefirst property is compatiblewith a Riemann surfacestructureand we will assume that our
Riemannsurfaces are Hausdorff
It is altman which will be a corollary
of something that we
connected
prove ltat aHausdorff Riemann
surface is 2nd countable
Example CHP
q2503
I Cz w tired
W I co073
Define an equivalence relationouw byCz w UN riff for some tox G w Ctu.tv
note to a 03
Writethe equivalenceclassofGut as Kiwifeta p be the set of equivalence classes
w clip
X toas
Hz w E if wt oCs w O
p Z WJ Iw Wto
as w O
Q 5 If we pull back the atlas on 5
to clip we got U Et i w wt03
Ur ft W 2 to
qiu 4 law E
if uz 94ft w Ee
ThisgivesQP a Reimann surface alterative