fractal geometry and fixed point theorem Banach
Introduction.
Let (E, d) a metric space complet.Pbf (E) denotes
all parties bounded and closed EK (E) denotes all
the compact subsets of E. We define on Pbf (E) Hausdorff distance
:
For A, B Pbf (E), D (A, B) = max (d '(B, A), (A, B))
or (B , A) = sup {d (x, A), x B} and (A, B) = sup {d (x, B), x in A};
d (x, A) (Resp . d (x, B)) denotes the distance from x to A (resp. B)
We prove that (Pbf (E), D) and (K (E), D) are complete metric spaces
.
Exercise.
iterated function (or ISF) on E, ie of a set of applications
{f_ {i}} (1
application k_ {i} strictly-contracting of E in E.
It defines a mapping F on K (E):
F (A) = U f_ {i} (A).
1
i) Check that K (E) is stable under F.
ii) Prove that F is strictly k-contracting or
k = max (k_ {i}, i = 1,2, ... n) (K (E) D) (K (E), D)
Deduce that there exists a C unique K (E) (called Attractor ISF)
as: C = U
f_ {i} (C).
1 C is a fractal.
iii) Show that for any x in C, F ^ {p} converges to x in C (K (E), D). <=i<=n),telle que chaque f_{i} est
iv) Examples.
a) in the real line.
Let f_ {1} {2} f_ and two applications of IR into IR defined by:
f_ {1} (x) = (1 / 3) x, f_ {2} (x) = (1 / 3 ) x +2 / 3. <=i<=n
is taken as initial value C_ {0} = [0,1]; check
that the fixed point of F, the iterations F ^ {n} (C_ {0}) is
the Cantor set.
b) in the plane. Write
the previous example in the plan, and draw
the first three iterations C_ {0}, C_ {1} and C_ {2}.
<=i<=n
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