Understanding Markov Models

From predicting the weather to generating Shakespeare, discover the "memoryless" math that powers modern Computational Linguistics.

Andrey Markov

(1856-1922)

"The future depends on the present, not the past."

The "Memoryless" Property

Imagine a system that "forgets" its history. It doesn't matter how it arrived at its current state; all that matters is where it is right now.

Developed by Russian mathematician Andrey Andreyevich Markov, this groundbreaking model is used in economics, physics, and notably, Computational Linguistics. Whether it's predicting stock volatility or the next word in a sentence, Markov models provide the foundation.

The Magical Box Simulation

The text describes a "Magical Box" that changes form based only on what it is right now.
Click the button to see the Markov Property in action!

ROBOT
Current State ROBOT
Next State Probabilities

Hidden Markov Models (HMM)

Sometimes the state is hidden (like treasure in a room), and we only see an observation (like the color of a box a guard carries).

POS Tagging

Imagine playing a game with word cards. One side has the word (Observable), the other has the Part of Speech (Hidden).

The happy puppy runs

DET ADJ NOUN VERB

HMMs calculate the likelihood of a sequence. "Adjective" often precedes "Noun", helping the computer guess that "Happy" is an adjective.

The Detective Game

Scenario: You see a guard carrying a RED BOX. Where is the treasure hidden?

Two Smart Detectives

Forward-Backward Algorithm

This detective calculates the probability of being in a specific state at a specific time, given the entire sequence of observations.

  • Sums up probabilities from all possible paths.
  • Looks both future and past.

Viterbi Algorithm

Unlike the previous detective, Viterbi is only interested in the single most likely path of hidden states.

  • Finds the best "route" through the states.
  • Like the hare in the race—always jumping to the best option.

Real World Applications

Speech Recognition

Turning sound waves (observed) into written words (hidden). HMMs handle accents, speed, and noise.

Named Entity Recognition

Spotting specific entities like names, cities, or companies in a wall of text using context patterns.

Text Generation

Learning the style of Shakespeare to generate new plays. Predicting the next word based on current state.