Fractal theory describes objects that have self-similar patterns across different scales. Fractals are defined as geometric shapes that can be split into parts, each of which is a reduced-size copy of the whole. They often have non-integer dimensions and fine structures at arbitrarily small scales. Common examples include natural shapes like coastlines as well as mathematical constructs like the Cantor set and Koch curve. Fractals are created by recursive processes that repeat a simple pattern on decreasingly smaller scales. Their dimension can be calculated from how their size changes with scaling factor.
Fractal? 1
Afractal is generally "a rough or fragmented geometric
shape that can be subdivided in parts, each of which is (at
least approximately) a reduced-size copy of the whole“ – (B.
Mandlebrot).
This property is called self-similarity.
3.
Graph Theory History2
Lewis Fry Richardson, “War & and Common
Border”
Benoit Mandelbrot, “How Long Is the Coast of
Britain”
4.
Properties 3
Afractal often has the following features:
It has a fine structure at arbitrarily small scales.
It is self-similar (at least approximately).
It is too irregular to be easily described in traditional
Euclidean geometric.
It has a dimension which is non-integer.
It has a simple and recursive definition.
Example (Creating) 5
Example: Cantor set.
The Cantor set is obtained by deleting recursively the 1/3 middle
part of a set of line segments.
7.
Example (Creating) 6
Properties of the Cantor set C:
C has a structure at arbitrarily small scale.
C is self-similar
The dimension of C is not an integer!
Length = limn->∞((2/3)n)=0. (But infinite points…)
8.
Example 2 (Creating)7
The Koch curve is obtained as
follows:
start with a line segment S0.
delete the middle 1/3 part of S0
and replace it with two other 2-
sides.
Subsequent stages are generated
recursively by the same rule
But >> limit K=S∞ !!
9.
Fractal Dimension 8
A mathematical description of dimension is based on how the
"size" of an object behaves as the linear dimension increases.
In 1D, we need r segments of scale r to equal the original segment.
In 2D, we need r2 squares of scale r to equal the original square.
In 3D, we need r3 cubes of scale r to equal the original cube.
10.
Fractal Dimension 9
This relationship between the dimension d, the scaling
factor r and the number m of rescaled copies required
to cover the original object is thus:
Rearranging the above equation: