What are the differences between genetic algorithms and genetic programming?

问题

I would like to have a simple explanation of the differences between genetic algorithms and genetic programming (without too much programming jargon). Examples would also be appreciated.

Apparently, in genetic programming, solutions are computer programs. On the other hand, genetic algorithms represent a solution as a string of numbers. Any other differences?

回答1:

Genetic programming and genetic algorithms are very similar. They are both used to evolve the answer to a problem, by comparing the fitness of each candidate in a population of potential candidates over many generations.

Each generation, new candidates are found by randomly changing (mutation) or swapping parts (crossover) of other candidates. The least 'fit' candidates are removed from the population.

Structural differences

The main difference between them is the representation of the algorithm/program.

A genetic algorithm is represented as a list of actions and values, often a string. for example:

1+x*3-5*6

A parser has to be written for this encoding, to understand how to turn this into a function. The resulting function might look like this:

function(x) { return 1 * x * 3 - 5 * 6; }

The parser also needs to know how to deal with invalid states, because mutation and crossover operations don't care about the semantics of the algorithm, for example the following string could be produced: 1+/3-2*. An approach needs to be decided to deal with these invalid states.

A genetic program is represented as a tree structure of actions and values, usually a nested data structure. Here's the same example, illustrated as a tree:

      -
   /     \
  *       *
 / \     / \
1   *   5   6
   / \
  x   3

A parser also has to be written for this encoding, but genetic programming does not (usually) produce invalid states because mutation and crossover operations work within the structure of the tree.

Practical differences

Genetic algorithms

• Inherently have a fixed length, meaning the resulting function has bounded complexity
• Often produces invalid states, so these need to be handled non-destructively
• Often rely on operator precedence (e.g. in our example multiplication happens before subtraction) which could be seen as a limitation

Genetic programs

• Inherently have a variable length, meaning they are more flexible, but often grow in complexity
• Rarely produces invalid states, these can usually be discarded
• Use an explicit structure to avoid operator precedence entirely

回答2:

Genetic algorithms (GA) are search algorithms that mimic the process of natural evolution, where each individual is a candidate solution: individuals are generally "raw data" (in whatever encoding format has been defined).

Genetic programming (GP) is considered a special case of GA, where each individual is a computer program (not just "raw data"). GP explore the algorithmic search space and evolve computer programs to perform a defined task.

回答3:

To make it simple, (on the way I see it) Genetic Programming is an application of Genetic Algorithm. The Genetic Algorithm is used to create another solution via a computer program.

回答4:

Practical answer:

GA is when using a population and evolve the generations of population to a better state. (For example how the humans have evolved from animals to people, by breading and get better genes)

GP is when by known definition of the problem generate code into better solve a problem. (GP will usually give a lots of if/else statements, that will explain the solution)

回答5:

Lots of good partial answers above. As Koza put it in his seminal texts on the subject, "[if a GA was the best solution for a problem then a GP would evolve a GA to solve it]." Simply put, a GP is a type of GA that evolves programs that are evaluated by a cost function. The fact that the genome is a program rather than a collection of inputs for the cost function IMHO is the material difference.

https://en.wikipedia.org/wiki/Genetic_programming

回答6:

genetic programming is much more powerful than genetic algorithms. the output of the genetic algorithms is a quantity while the output of the genetic programming is another computer program.

来源：https://stackoverflow.com/questions/3819977/what-are-the-differences-between-genetic-algorithms-and-genetic-programming