Math midterm

A non-empty plane set

Motif

Repetitions of a motif in the plane

Pattern

4 types of Transformation Isometries

Rotation, translation, reflection, dilation

Turns a figure about a certain point in a plane; an isometry

Rotation

Slides a figure in any particular direction or a distance; an isometry

Translation

Mirrors a figure of a line known as the axis of symmetry; isometry

Reflection

Shrinks or expands a figure by some scaling factor; not an isometry

Dilation

A combination of reflection and a translation

Glide reflection

The original figure and the resulting figure are congruent

Isometry

The composition of isometries in the plane; mapping the pattern in the plane back itself

Symmetry

Has only reflections and rotations; has a center point

Rosette patterns

Dihedral group; a symmetric group involving seven reflections and 7 rotations

D7

A symmetry of twelve rotations

D12

Has reflections and rotations; also has translations and glide reflection but only along one line; the distance of translation is minimum/fixed

Frieze pattern

Only involves translation

Hop

Glide reflection symmetry; translation and reflection

Step

Translation and vertical reflection

Sidle

Translation and rotation (120*)

Spinning hop

Translation, glide reflection, & rotation at 180*

Spinning sidle

Translation and horizontal reflection

Jump

Contains all symmetries

Spinning jump

Translation symmetry is added in a second, independent direction; has 17 groups; patterns extend infinitely in all directions

Wallpaper groups

A pattern covering a plane by fitting together replicas of the same basic shape

Tesselation

The father of tessellation

Maurits Cornellis Escher

A tessellation made up of congruent regular polygons (triangles, square, hexagon)

Regular tessellation

Also known as Archimedean tessellation; regular tessellations of two or more different polygons around a vertex; each vertex has the same arrangement of polygons

Semi-regular tesselation

An edge-to-edge tessellation, but the order or arrangement of polygons at each vertex is not the same

Demi-regular tessellation

A geometric pattern that is repeated at a smaller scales to produce smaller shapes and surfaces that cannot be represented by classical geometry

Fractals

Repeating a process or function

Iterations

The method for generating fractals

Iterative function system

Comes out of a rule goes back into the rule for the next iteration

Recursion

A fraction used to specify the distance from one plotted point to the next relative distance

Scaling factor

The number of distance measurement needed to specify the size of an object in the eudidean world

Dimension