In topology, the concept of homeomorphism is crucial, as it establishes when two spaces can be considered equivalent, involving continuous mappings with continuous inverses. Topological spaces have various properties, including open and closed sets, neighborhoods, and limit points.
Homeomorphism (homeomorphic mapping)
is a mapping f: (X,Tx) --> (Y, Ty) s.t.
f is continuous and inv(f) is continuous
(X,Tx), (Y,Ty) HOMEOMORPHIC ≈ Spaces
if there is a homeomorphism between the spaces
Symetric
(X,Tx) ≈ (Y,Ty) and (Y,Ty) ≈ (Z,Tz)
then (X,Tx) ≈ (Z,Tz)
Symetric
(X,Tx) ≈ (Y,Ty) then (Y,Ty) ≈ (X,Tx)
Reflexive
(X,Tx) ≈ (X,Tx)
complexes
cell
cubic
simplicial
CONVERGENCY IN (X,Tx)
of sequences of elements xn in X
SEQUENCE xn in X CONVERGES to L if:
For an U in the veninity of L V(L) or open O s.t L in O
enxist a natural numner N S.T.
for all n >= N then xn is in U
For (X,Tx) to (Y,Ty)
f continuous mapping
xn sequence converges to L in X
if yn=f(xn) then
yn converges to(f(L) in Y
if Tx is discrete topology
only xn becoming in constant converges
For X stronger xn is hard to converge
xn can converge to several elements of X
(X) Set / Collections
(T) Topology
Family of subsets of (X) Axiomatic definition of open sets (O)
Intersection of topology is a topology
Discrete Topology T_d
All subset of X
Power set
Usual Topology on R
O ∈ T iff ∀x ∈ O ∃ǫ > 0 : ]x − ǫ, x + ǫ[⊂ O.
Trivial Topology (X,T_t)
{X , empty set}
Or alternatively by a axiomatic system of neightborhoods
sets
vertices
Ingteger numbers
Subtopic
Real numbers
( f ) Mapping between
topological spaced
(X,Tx) to (Y,Ty)
Conbtinuous "on X"
f:(X,Tx) ---> (Y, Ty)
if is continuous for all points of X
Continuous Real Mapping
f:(X,Tx) ---> (R,TR)
( f ) Continuous "at point x0"
if yo=f(x0) and for a neighborhood of yo Ny
exist a neigtbohood of x0 Nx such that
f(Nx) included in f(Ny)
CONTINUOUS MAPPING
if the image of every OPEN W in Y is an
OPEN in X ; this is inv(f(W)) is in Tx
THEOREM: f: X --> Y, and g:Y --> Z
f continuous map, g continuous map then
g · f : X --> g(f(X)) in Z
IS CONTINUOUS
THEROREM : f:(X,Tx) ---> (Y, Ty)
IS CONTINUOUS ALSO IF
if the image of every CLOSED W in Y is an
CLOSED in X
THEROREM : f:(X,Tx) ---> (Y, Ty)
IS CONTINUOUS ALSO IF
Tx is stronger topology than Ty
Comparison of Topologies
T1 is Stronger Topology than T2
if every open of T2 is an open of T1
T2 Weaker Topology than T1
if every open of T2
is an open of T1
Open Sets (O)
Elements of (X,T)
Neighborhood of
points x in (X,T)
Interior
Larger open set in a set A in (X,T)
Limit Points
not in Boundary
Contact Points
in the Boundary
adherent point
"closure point "
point of closure
Closure of barra A
Set of all contact points of A
properties
Morgan Laws
Closed Set
Complements of (O)
Fundations
Topological space (X,T)
x in (X,T) are points
FINAL TOPOLOGY
Minimal topology on X that
make any mappinf
fi : X --> Y
Connected Topological Space
if only Vacio and X are unique
open close subset
Density in (X,T)
A dense in X if \A=X
A nowhere dense
if is no dense in any subset
The product topology
Result of create Opens that unite two topologies:
ej. R2= RxR
THE TRACE
system of subsets of a subset on (X,T)
RELATIVE OR INDUCED TOPOLOGYSub topological space of subsets of (X,T)