• Home
  • All Posts
  • Tags
  • About
  • Atom feed
Swans & Swan

Computability and Complexity

Regular Languages July 8, 2023 8 minute read

Finite Automata

Finite automata are good models for computers with an extremely limited amount of memory. The controller moves from state to state, depending on the input it receives. Finite automata and their probabilistic counterpart Markov Chains are useful tools when we are attempting to recognize patterns in data.

Formal Definition of a finite automaton

​ A finite automaton is a list of those five objects: set of states, input alphabet, rules for moving, start state, and accept states.

Definition A finite automaton is a 5-tuple $(Q,\sum,\delta,q_0,F)$, where:

  • $Q$ is a finite set called the... read more

Computational Geometry

Robot Motion December 16, 2022 3 minute read

Given a robot and set of obstacles, find the shortest path from $s$ to $t$ without collision.

image-20210318143348856

Robot without collision volume

Starting from a point $s$ and finds a possible way to the end point $t$.

First, build a rectangle boundary and do the planar subdivision, pick the mid point for vertical planar edge and pick the mid point for ever face.

Find the shortest path from the face $f_s$ containing $s$ to that $f_t$ containing $t$. Add an edge from $s$ to the nearest face middle point and add an edge from that... read more

Delaunay Triangulations December 16, 2022 8 minute read

A terrain is a 2-dimensional surface in 3-dimensional space with a special property: every vertical line intersects it in a point, if it intersects it at all. In other words, it is the graph of a function $f:A\subset \mathbb{R}^2\rightarrow\mathbb{R}$ that assigns a height $f(p)$ to every point $p$ in the domain, $A$, of the terrain.

image-20210317132256993

Nevertheless, some triangulations look more natural than others. We will rank triangulations by comparing their smallest angle. Since there is only finite number of different triangulations of a given point set $P$, this implies that there must be an optimal... read more

Voronoi Diagram December 16, 2022 7 minute read

Problem: Given a set $S$ of $N$ points in the plane, for each point $p_i$ in $S$ what is the locus of points $(x,y)$ in the plane that are close to $p_i$ than to any other point $S$ ?

Definition locus is the set of points whose location satisfies by one or more specified conditions.

Given two points, $p_i$ and $p_j$, the set of points closer to $p_i$ than to $p_j$ is just the half-plane containing $p_i$ that is defined by the perpendicular bisector of $\overline{p_ip_j}$. Denote the halfplane by $H(p_i,p_j)$. The locus of points closer to $p_i$... read more

  • Computability and Complexity (1)
  • Computational Geometry (8)

    2023 © Thomas Men

    Posts
    Tags
    About