Affine plane, block design

This design has $n+1$ blocks, each containing $n$ points, with each point appearing in $n+1$ blocks. This corresponds to a block design with $v=n^2$, $k=n$, $\lambda=1$, $r=n+1$, and $b=n+1$. Therefore, for AG(2,q), there are $q+1$ groups of parallel lines and each group contains $q$ lines.
  • #1
andreass
16
0
I'm trying to understand some things in finite geometries, more specific - affine geometry.
Now I'm reading some notes and wiki:
http://en.wikipedia.org/wiki/Finite_geometry
http://en.wikipedia.org/wiki/Block_design

I would like to know how many groups of parallel lines are in affine plane AG(2,q) and how many lines are in each of those groups?

For example AG(2,2) correspond to (v=4,k=2,lambda=1,r=3,b=6) which means affine plane consists of 4 points, 2 points on each line, 2 points have only 1 common line, each point lies on 3 lines and there are 6 lines together.
block.png

We can see in image that there are 3 groups of parallel lines (each color is 1 group) and there are 2 parallel lines in each group. Does it somehow correspond to block design (e.g. r=3 or k=v*r/b=2)?
 
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  • #2
Thanks.A:In an affine plane of order $n$, there are $n+1$ groups of parallel lines and each group contains $n$ lines. The arrangement of the lines in an affine plane of order $n$ form a $2-(n^2,n,1)$ design, which is also known as a projective plane.
 

What is an affine plane?

An affine plane is a two-dimensional geometric structure that satisfies certain axioms, such as the existence of parallel lines and the ability to perform transformations such as translation and rotation.

What is a block design?

A block design is a statistical design used in experiments to determine the effects of different treatments or factors on a response variable. It involves dividing the subjects or units into groups, or blocks, and randomly assigning treatments within each block to reduce bias.

How are affine planes and block designs related?

Affine planes are often used in the construction of block designs, as they provide a way to partition the experimental units into blocks. This allows for a more efficient and accurate analysis of the data.

What is the difference between an affine plane and a projective plane?

An affine plane is a subset of a projective plane, with the main difference being that an affine plane does not include points at infinity. This means that parallel lines in an affine plane never intersect, whereas in a projective plane, they intersect at a point at infinity.

What are some real-world applications of affine planes and block designs?

Affine planes and block designs have many practical applications, such as in agricultural experiments, clinical trials, and market research studies. They are also used in coding theory and cryptography to design efficient and secure communication systems.

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