## Wednesday, October 31, 2012

### Monotone increasing sequences

Monotone increasing functions preserve some ordering relation. In this case, we will consider functions and sequences that are increasing in quantity such as those produced by range:
(= (range 4) '(0 1 2 3))

Ranges are all increasing by one. However, some values may be increasing to an increasing extent. This can be determined by the antireduce function:
(= (antireduce - '(0 1 3 6 10))
'(0 1 2 3 4))

The triangular numbers are produced by additively reducing over the range and tetrahedral numbers are produced by using the same process on the triangular numbers. The fibonanci numbers are the additive reductions of themselves. Furthermore, the factorial function is produced by the multiplication reduction over the range.

## Thursday, October 25, 2012

### Ordering relations

The nodes a preorder can be partitioned into sets of equivalence classes such that for any ordered pair of nodes in an equivalence class there is a path between the two nodes. Every preorder is determined up to isomorphism by a partial ordering of its equivalence classes. Here are several types of preorder relations:
• Equivance relation: the partial ordering relation is empty
• Partial order: every equivalence class is trivial
If the partial ordering relation doesn't contain any undirected cycles that are greater then size two then it forms a tree. It is relatively easy to canonize directed trees and equivalence relations up to isomorphism by describing their shape. However, canonizing ordering relations that contain oriented cycles like the reachability partial order on {A -> B, A -> C, B -> D, C -> D} is a relatively complicated process.

Every relation has a reachability relation associated with it that preorders all nodes in terms of rather or not there is a path between them. Functions have a reachability relation between elements that is a tree of equivalence classes, and since permutations are the union of disjoint cycles their reachability relation is an equivalence relation.

## Wednesday, October 24, 2012

### Physical computing

My understanding of computing is largely based upon physical principles such as orthogonal persistence and the conservation of information:
• Orthogonal persistence: state is represented with directly modifiable objects that don't require specific save / load actions.
• Conservation of information: information cannot be created or destroyed, it can only be transferred and transformed.
Conversation of information is the basis of universal undo, which along with orthogonal persistence is a principle of good user interfaces. Parallelism is also a physical property, as there are always many things happening simultaneously at different places in the universe.

I believe that 21th century advances in self-configuring modular robotics will lead to programmable matter. Advancements in this area will unite physics and computing.

## Friday, October 19, 2012

### Mereological placehood relations

Common Lisp place forms are extended to become first class read-write (RW) parts and mereological methods are used as a method of reasoning about these place forms. Associations are introduced as data structures that explicity relate a set of independent places with a set of corresponding values.

https://github.com/jhuni/Placehood-relations/blob/master/Report.pdf?raw=true

## Tuesday, October 2, 2012

### The shape of an equivalence relation

Every equivalence relation has a multiset of equivalence class sizes associated with it that completely describes that equivalence relation up to relation isomorphism. For example,
(= (shape #{#{1,2,3} #{4 5}, #{6 7} #{8}})
{3 1, 2 2, 1 1})

Divisions are precisely those equivalence relations that have only one distinct element in their multiset, so they evenly divide a set into parts:
(= (shape #{#{1,2}, #{3,4}, #{5,6}, #{7,8}})
{2 4})

The division shapes {∞ 1} and {1 ∞} are the bottom and top level shapes, because {∞ 1} has no parts and {1 ∞} is the universal element that contains everything as a part. Place forms have divisions as their equivalence relation, such that the top place form is the identity function.