Week 4 Flashcards
Is a traditional crossover geometric?
A traditional crossover is geometric under the hamming distance (difference between your result and your two original solutions)
What is semantics of a program?
All input output pairs defining the computed function
What are semantic operators?
Semantic operators act on the syntax but guarantee that some semantic criterion holds
- semantic mutation: offspring semantically similar to parents
- semantic crossover: offspring semantically intermediate to parents
Advantages of GP with geometric semantic operators
Always sees a cone landscape that is easy to search
Why Swarm intelligence?
Swarms, flocks, etc… often exhibit the rather interesting properties:
– Individuals of the swarm are incapable of X, or could do X with only low probability.
– However, the swarm as a unit is able to do X, with high probability.
The ability to do x is an emergent property of the swarm.
How do swarms communicate
Each element of the swarm has its own simple
behaviour, and a set of rules for interacting with
its fellows, and with the environment.
* Every element is the same – there is no central
controller.
* However, X emerges as a result of these local
interactions.
* E.g. ants finding food, termites building mounds.
How do ants perform complex tasks?
Ants have highly developed sophisticated sign-based stigmergy
Communicate using pheromones that can be followed by other ants
How do pheromone trails work
Individual ants lay pheromone trails while travelling from
the nest, to the nest or possibly in both directions.
* The pheromone trail gradually evaporates over time.
* But pheromone trail strength accumulate with multiple ants
using path.
* Ants prefer paths with more pheromone on them
How does ant colony work
Ants are agents moving along nodes in a graph
Choose where to go based on pheromone strength
Ant path is a candidate solution
