Is positive thinking positive or negative?

There are many articles, books and seminars that sing praises to positive thinking, so how could it be negative?
Negative has a negative connotation, if you excuse the circularity.
Nobody wants to be negative, just why I don't know. Having a negative debt is actually a good thing.
The opposite of positive thinking is presumably negative thinking, which is always looking for mistakes in others and in ourselves. Hence positive thinking must be positive.

But......
There are criticisms on positive thinking, mostly saying that positive thinking is self-delusional .
In the following, we present three views, the first agrees with positive thinking, but goes one step further, the second critical to positive thinking, and the third goes beyond the framework of the question in the title of this posting.

In "The Hidden Rule of Positive Thinking" Rob Spiegel said he believes in positive thinking, argues its benefits, and at the end he said that it should lead to positive giving: "The final element of positive thinking is positive giving. There’s a hidden agenda that lives as the subplot to positive thinking – what you receive is not yours to horde – it’s yours to pass. Sometime in the third of fourth book written by a positive thinking guru, you’ll begin to find a subtle shift in the thinking, a shift from grabbing to giving."

Steve Pavlina wrote in "Beyond Self-Delusional Positive Thinking", " I don’t do daily affirmations or recommend them to others because I think they’re a waste of time. Too much positive thinking can lead to self-delusion. You experience a false sense of growth because you lower your awareness, blinding yourself to your problems instead of truly facing them. As a general rule of personal development, whenever you do something that lowers your awareness instead of raises it, you’re making a mistake."
Instead Pavlina recommends "self-trust, awareness, and fearlessness. Note that positive thinking isn’t one of them" for personal growth.
Pavlina continued: "The solution to irrational fear isn’t to adopt positive thinking and try to overwrite the fear with affirmations. That’s just dumb. The real solution is to turn on our wonderful brains and dive more deeply into our fears in order to really understand them. Underlying irrational fears are irrational assumptions about reality. Once we can see this clearly, it’s natural and normal to simply drop those irrational assumptions altogether."

In his book "Wherever You Go, There You Are", Jon Kabat-Zinn who is also the author of "Full Catastrophe Living: Using the Wisdom of Your Body and Mind to Face Stress, Pain, and Illness", a medical professor and an expert in stress management, puts it very nicely(in the chapter "Meditation: not to be confused with positive thinking"): "If we decide to think positively, that may be useful, but it is not meditation. It is just more thinking. We can as easily become a prisoner of so-called positive thinking as of negative thinking. It too can be confining, fragmented, inaccurate, illusionary, self-serving, and wrong. Another element altogether is required to induce transformation in our lives and take us beyond the limits of thinking."

I do not deny that there is some value for positive thinking, just think what Churchill said about "blessings in disguise". People with Kaizen philosophy look for problems, they create them if necessary, for "problems are a mountain of treasure".

In meditation, we go beyond positive and negative dualism, and we go beyond thinking. When we encounter a situation where there are bad and good things, we can choose to emphasize the good or the bad, but in meditation we embrace them all as part of ourselves.

The mystery of the ubiquity of the power law

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"Power laws are found in a wide range of different systems: from sand piles to word occurrence frequencies and size distribution of cities. The natural emergence of these power laws in so many different systems, which have been called self organized criticality, seems rather mysterious and awaits a rigororus explanation" - Levy & Solomon, Dynamic Explanation for the Emergence of Power Law in a Stock Market Model

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Why is the power law so ubiquitous? It is found in the distribution of city sizes, in word frequencies, in wealth distribution, company sizes, and even baby names. Apart from the Gaussian normal distribution, it is probably the most frequently found distribution beside the exponential and Poisson distributions.
Intuitively, we think we understand how the normal, exponential and the related Poisson distibutions come about, but the power law? Normal distribution arises out of imprecision or error conditions. The exponential distribution is natural for growth processes, and Poisson distribution describes naturally the occurence of events independent from each other.

Let us start with stating the power law:

f(x) = a.x^b, where a and b are constants, can be fractional and negative

It is amazing how should a simple equation is related to so many complex phenomena, such as the edge of chaos and fractals.

A special case is the Zipf's law:

f(r) = C.r ^-1, here f is frequency, and r is rank

Zipf was one of the first who stated the power law when investigating frequencies of words, the frequency of a word is inversely proportional to its rank. It was an empirical law, and Zipf had later tried to explain it as a consequence of the "Principle of Least Effort".

Pareto's law (80-20 rule) on the distribution of wealth is another example of a power law.

Per Bak et.al. wrote a very influential paper in 1987, they introduced the concept of self-organized criticality (SOC) first found in statistical physics, but now applied to diverse fields as geophysics, physical cosmology, evolutionary biology and ecology, economics, sociology, and the world wide web.
The critical state of SOC lies in the border area between order and chaos, or commonly known as the edge of chaos, where it is believed that all really creative processes occur: to much order is boring, and chaos is often just not manageable.

Bak et.al. used a sand pile model to illustrate it, when in critical state, a single grain of sand could cause an avalanche. The size of avalanches obeys a power law.
Note that the power law connection to SOC has only been observed, not proven.

It is also not known what exact conditions give rise to SOC, and hence the mystery of the ubiquity of the power law remains.

Intuitively, power laws can arise when there is competition of a limited resource, such as cities competing for inhabitants, or companies competing for market share, or websites competing for visitors.
For an interesting application of the power law to weblog traffic see Clay Shirsky's article :"Power Laws, Weblogs and Inequality".
If so, does it mean that inequality of wealth must be taken as something natural and accepted as fair?

An imaginary equal share of wealth is definitely not stable, a little bit of luck could cause one component to have an early advantage, which in turn can widen the gap.

The other extreme is a winner-take-all situation, where the market collapses to a monopoly or duopoly. The ubiquity of power laws would sugest that monopolies are generally not considered fair. It would be outlawed, or the other players simply would not play the game, and invent a new kind of game.

Debugging mind viruses: Clear Comprehension.

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"Take the life-lie away from the average man and straight away you take away his happiness." Henrik Ibsen: The Wild Duck

"But yet the light that led astray
Was light from Heaven." Robert Burns: The Vision

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This is a continuation of the posting Debugging Mind Viruses, where Clear Comprehension is mentioned together with Bare Attention, as the two parts of Insight Meditation. Bare Attention and Clear Comprehension are complementary to each other, each supporting the other.

It is said that Bare Attention cannot be sustained for a very long period. In our terminology, Bare Attention is debug mode, and we cannot stay in debug mode all the time, we have to attend to our mundane tasks. Clear Comprehension, on the other hand, is recommended, to be practiced at all times, except when sleeping. The expression, to be mindful at all times, it to be understood in this way.

With regard to debugging mind viruses, Bare Attention, concentrates on one object at a time. It is based on the observation, that no two objects can occupy our mind at the same time.
All relations of the object are severed instead of being followed, our judgement suspended, so that the object can be seen as it is.
In the computer analogy, with Bare Attention, we can see all the processes that is currently running in the computer.
But, how do we know which process is a malignant virus, and which are processes necessary for the functioning of the computer? An expert should be able to distinguish them easily. Some viruses, however, attach themselves to normal running processes, and even more sophisticated viruses use stealth techniques to escape detection. If this sounds complicated enough, the task of debugging mind viruses is even more daunting.
There is no guarantee that anyone can ever achieve total purification of the mind, devoid of any mind viruses.
In ancient times, it is believed that wise ages have been able to achieve such feats. Today we owe them and their disciples for the teachings, and practices they left for future generations.
The world has in the mean time grown much in complexity compared to 2000 years ago. Civilization, life, and with them mind viruses have grown ever more complex. I believe that the chance of achieving purification of the mind, has diminished compared to back then, although the possibility is not equal to nil. Anyway, a 80% purification or even just 40% is still much better than none at all, and we will not know until we practice it. A wise man of today would probably achieve enlightenments several times in his life, but never fully immune from the ever mutating mind viruses.

Returning to the topic of Clear Comprehension, we can see it as complementary to Bare Attention, it picks up where Bare Attention left out. Bare Attention cannot distinguish between harmful and neccesary mind objects, this is where the wisdom of Clear Comprehension comes into play.

According to Insight or Vipassana Meditation (see for example Nyanaponika Thera: The Heart of Buddhist Meditation), Clear Comprehension consists of four comprehensions:

1. Clear Comprehension of Purpose
2. Clear Comprehension of Suitability
3. Clear Comprehension of the Domain (of Meditation)
4. Clear Comprehension of Reality

The first states that before every action, one should examine whether it would be in accordance with our goals, aims, and ideals. Some actions might cause great regrets afterwards. We cannot simply assume that man will always act rationally, particularly if the man is infested by mind viruses, just as we cannot entrust an infected computer to keep our files uncorrupted!

The second says that suitability depending on the internal and external environments should be considered in acting.
If the first comprehension is rather idealistic, the second is practical, adaptible, and flexible. This sounds almost like optimization problems in operations research: optimize goal under the satisfaction of constraints.

The third comprehension is understanding the specific domain, where our actions apply. When playing football, the domain is of course football. But we must make this domain a meditation object or in other words, in every of our actions in daily life, such as eating, walking, running, reading, talking, driving, playing, we should be mindfull.

The last comprehension is understanding what is real and what is virtual, and what is a delusion. There are innumerous delusions that we encounter, in Buddhism, the mother of all delusions is the self delusion.
In Buddhism, the doctrine of nonself (anatta) is one of the three universal characteristics.
Impermanence is quite easy to accept, all things change, the only permanent thing is change itself.
Incompleteness is not hard to understand when we know Goedel's incompleteness theorem or Heisenberg's uncertainty principle or even the second law of thermodynamics. It also manifests itself in day to day life as various sufferings, sickness and death.
Nonself is however much more difficult to stomach than the other two characteristics. Nonself entails also no soul, and no reincarnation. This is often misunderstood, rebirth and reincarnation are different. The process of rebirth is just one breath after another, there is no identity of any kind being preserved in the transition.
How can we deny a self, when we are dealing with me and you all the time?
It is precisely this, why it is called the great delusion. It took me 50 years to begin to understand this, understand here meaning not just intellectually, but to understand with the heart.
The topic of nonself shall be covered in another place, suffice it to say that the most dangerous mind viruses are related to this delusion.
All sorts of problems arise from comparisons "I am better/worse" and possessions "this is mine", " this is ours", etc.
Mind viruses certainly find self delusion as the most important security hole to get into our minds. Advertisements know how to exploit this very well to sell us their products. Flattery is another trap for the self.

The self delusion also applies to groups of people, it is then called a group self delusion. Groups of closely related people often are infected by the same virus, but only outsiders can be aware of it. It is interesting to observe that sometimes the virus is that binds the group together! Think about hate campaigns, hate Mr X, spreading and exchanging jokes about the stupidity or clumsiness of Mr X via SMS and the internet.

All the above four comprehensions are taught in Insight Meditation. They will be very useful in detecting mind viruses, and also preventing us from getting us new ones. They are anti-viruses that heal and protect.
People from different creeds or from different spiritual communities, may formulate the comprehensions in slightly different ways, but they certainly have their goals, constraints, contemplations and what they consider the most important delusions.
Richard Dawkins, who wrote "The God Delusion" presumably would say that the God delusion is the root of all evil.
We may or may not agree with other people's life principles and world views, to say that ours is the only correct one, would be to fall into the self righteousness, which is again a self delusion.
What A considers a delusion, B may consider as the very foundation of her existence. Practicing meditation is one practical way to find out who is right and who is wrong. Shooting each other is not a recommended way to find out.

It would be interesting to conduct a poll what people think is the greatest delusion of all, but the results would mean no more than a popularity contest.

Clear Comprehension is thus different from Bare Attention. Bare Attention is basically the same for different people because it is value neutral. Clear Comprehension is wisdom, and as such very much dependent on our beliefs.

Debugging Mind Viruses

The idea that our minds are infected by viruses is not new. Here we mean viruses as analog to computer viruses (Technically, we use the term virus as a general term to include also worms, spyware, Trojans and other types of malware), not biological viruses. Richard Brodie wrote a book titled “Viruses of the Mind”, with the subtitle “The New Science of the meme”. Meme is thought to be the unit carrier, whereby viruses spread and proliferate. Brodie wrote: “Mind viruses have already infected governments, educational systems, and inner cities, leading to some of the most pervasive and troublesome problems of society today: youth gangs, the welfare cycle, the deterioration of the public schools, and ever-growing government bureaucracy.” In this posting, the author discusses techniques of debugging such viruses. It starts with slowing down, one pointed concentration, bare attention, and ends with reflection, and effort and practice.

Computer programs, except for the simplest school book examples, always have bugs, i.e. programming errors. That is why we have so many update releases and service packs. Yet the service pack itself introduces new bugs! As software grows more complex, the number of bugs increases exponentially. Software also ages, the longer it has been in use, the more likely it is to be in disharmony with the original specifications and/or with the changing environment it is supposed to handle. Additionally, software is often used in an open environment such as the internet, and the bugs are no longer just programming errors, but malware from infections.

The mind is definitely so much more complex than a computer program, quantitatively and qualitatively. It does not take a lively imagination, to see that mind viruses are so much more abundant, fatal and difficult to debug. There are no anti-viruses, which you can simply buy and use to clean our minds. Debugging our minds is inherently difficult, because we have first of all, to admit that we carry viruses, and be willing to scrutinize our ego, habits and world views. Even when we rationally recognize a virus in our minds, we still need considerable discipline to overcome it. Just think about overeating or quit smoking.

The mind debugging techniques discussed here are derived from age-old methods of liberation and purification of the mind. We will see some parallels as well as differences of these methods with computer debugging.

Basic techniques:

The processes in the mind are intricate and interlinked. Just as in computer debugging, we have to do unit testing before we do integration testing. Make sure that each component is functioning as they should, before considering the component’s interaction with each other. If processes are running parallel, we need to consider one particular process in isolation first. This is the technique of One Pointed-ness: concentrate on a single object. Don’t do multi-tasking. Don’t watch television or read the newspaper while eating, don’t answer the phone while simultaneously signing contracts. In the extreme, one should not sing while bathing. To some, this is contrary to what they normally do. Many also think that without multi-tasking, we are not functioning efficiently. There are two different opinions here, one considers debugging as a sort of cleansing process, after which we can return to our normal daily activities. The other says that we have to strive to do debugging at all times, anywhere. Here we only say that there are debug and normal modes, it is possible and desirable for some to in debug mode all the times.

Concentrating on a single object is hard enough. It may be a fast running process. Therefore slow down, trace each step one by one. We are so accustomed to rushing from place to place, from one object to another, from one activity to another, that we become impatient when things slow down. But many people familiar with stress reduction have come to the same recipe: slow down!

The third technique is Bare Attention, seeing things as they are without trying to do anything. Just noting, not labeling, not making inferences nor judgments. Suspend our thinking, just note what happens, breathing in, breathing out. When we have developed this technique to a certain level, we can discern finer things which we normally miss. Our body sends messages to us all the time, but we practically ignore them until one day we discover that we have a serious illness. Nature talks to us in many forms, but we keep destroying the very foundations of life on earth by pollution, cutting down trees, killing plant and animal species. Bare Attention to our to body, mind and to nature will help us to be aware of the messages they send. If a virus infects our mind, they will somehow manifest themselves, and Bare Attention will be aware of their existence. In theory at least, for there are many hindrances to this process; anger, emotion, desire, illusion, attachments can all make the view muddy and turbulent, and prevent Bare Attention to see through.

Bare Attention can be practiced by sitting in meditation, relaxing, and noting our breaths. Our minds will then wander like a monkey, sounds come from all around, sometimes a mosquito bites us, our body aches or we remember someone who has done us wrong in the past eliciting emotions. In Bare Attention we note everything that comes, without judgment, and return to our breath as soon as possible. When we are angry, note the feeling of anger, when a memory arises, be aware of it, and when we desire to quit the meditation, note it also. After our minds are quieter, we will be able to discern not just the fact that something is, but also its arising and passing away. We let things speak for themselves.

Bare attention can be called radical acceptance of the present moment. It is definitely not possible to practice bare attention while wandering to the past or future, or to dream of other places. It therefore ties together with the principle of Here and Now. Za Choeje Rinpoche, in a guided meditation tape, said: “ Meditation is simply the art of living in the present moment. The purpose of meditation is to remain in a state of calm abiding and to relax into our true nature”.

Not being here and now, means we are lost, living in some virtual reality built from memories, illusions and fantasies. To always abide in here and now is a very powerful weapon against mind viruses. By being here and now, we can keep in close touch with reality.

The techniques mentioned so far, One Pointed-ness, Slowing down, Bare Attention, are all connected with each other and with the principle of Here and Now.

It is important to point out, that during the practice, there are two very different processes going on. One is the concentration on an object such as breath, and the other is the noticing of whatever comes into the mind. The second process is unpredictable and chaotic. In order that the practice be beneficial, the first process must dominate, we must only notice the events interrupting the first process, but we must not follow them, we go back to the first process as soon as our awareness allows. The first process is the anchor without which there will no structuring, and chaos will take over. This theme of chaos and order is quite common in other areas. A good architecture is never a complete chaos. Nor is it just order. The order, symmetry and symmetry breaking, and some chaos confined within the order is what makes the architecture a work of art.Insight Meditation consists of two parts, Bare Attention and Clear Comprehension. Bare Attention must precede Clear Comprehension. However, by itself, Bare Attention is not sufficient to understand and reflect our mind. This is where Clear Comprehension comes in, which will be discussed in a follow-up post.

Memes as classes and patterns with emotional attachments

In 1996 Brian Foote and Joseph Yoder wrote “The Selfish Class” , a very important paper giving a code’s eye view of software reuse and evolution. Of course the analogy is with Richard Dawkins’ gene’s eye view in his book “The Selfish Gene”. Foote and Yoder discussed attributes of successful classes such as “works out-of-the-box” and “low surface-to-volume ratio”.

Our focus here also deals with classes in the sense of object-orientation, but we discuss them in relation to the representation of memes, another term coined by Dawkins.

The Wikipedia entry says that a meme refers to a unit of cultural information that can be transmitted from one mind to another. Dawkins said, Examples of memes are tunes, catch-phrases, clothes fashions, ways of making pots or of building arches. A meme propagates itself as a unit of cultural evolution analogous in many ways to the gene.

What is this unit of cultural transmission? Will we ever find something like a DNA, the chemical molecules of genes? We don’t think so.

We suggest that memes are classes and patterns (note: patterns are sets of classes which cooperate and work together in a certain way, see e.g. the gang of four’s book ),

and hence are bits of information or software in our brains. Should we, one day, be able to extract the information content of our brains, we might be able to read those classes and patterns.

We say that memes are classes, and not just any bit of information, because classes encapsulate both attributes and procedural knowledge. A tune, for example, has the attributes the composer, the singer, dates, but also the music itself encoded as a procedure.

Origami technique of paper folding to make a ship is another example of a class with coded instructions.

Sometimes a class is not sufficient to represent a meme, the Romeo and Juliet meme for example, consists of entities with specific relations to each other, and a certain sequence of events. We propose to represent such memes as patterns. In the pattern, a class has a certain role, and classes and send messages to other classes to do something. This fits in very nicely with Dawkins view of communication, not as information exchange, but as manipulation.

Other more complicated memes such as the notion of a deity can be represented as more complicated patterns.

The consequence of looking at memes as classes is that all properties of object-orientation would apply: instantiation, abstract classes, inheritance, and messaging. One meme such as a joke could involve a bicycle or motorcycle, or an abstract 2 wheeled vehicle.

Memes actually exist in different forms, a passive storage such as books, active in our minds, or on the internet and computers, or as unwritten traditions and customs. The distinction is between active and passive, and between vehicles that only stores, and those that can manipulate and propagate. Human minds can modify memes and can propagate them. Libraries are only passive repositories. Computers if programmed to do so, can manipulate and propagate memes. TV commercials are basically programs showing multimedia content and in so doing help propagate memes.

We therefore have the following categories of meme repositories:

1. passive libraries
2. human minds
3. tools for propagation such as computers, media, and internet

The third category needs to be programmed by human beings. One day perhaps, with advanced artificial intelligence, computers could be more than just tools.

Returning to our classes and patterns, in categories 1 and 3 memes are just information, whether procedural or not. In the second category, a meme is not just a piece of information, it has emotional attachment to the host. Think about many products where the brand name actually has more prestige value than the products actual utility value.

Many memes will be competing for our attention, but only few will have a strong attachment to us, just like a suicidal terrorist infected by a doctrine. The attachments are changing all the time, one time we may be entirely occupied by earworms (songs that one can't stop humming or thinking about), just like a computer under a DOS (denial of service) attack, at other times our minds could be serene in mediation with minimal attachments.

The attachments are obviously just as important as the content.

Hence our title: memes as classes and patterns with emotional attachments.

We shall later explore this further and deal with debugging memes that are mind viruses using meditation techniques.

What is the consciousness before you were born?

This sounds like a Zen Koan. The simple answer is: the unborn consciousness. To understand what it really is, we will first look at the multiple levels of consciousness (or awareness).

The first five levels deal with sensory perceptions corresponding to the five sensory organs, sight, hearing, smell, taste and touch.

The sixth level is where we have thought, feelings, and memory. This level integrates the first five levels. Logical thinking and problem solving belong to this level.

The next level differs from the sixth, it is the unconscious level. It may be strange to regard unconscious as one of the consciousness levels, but it is certainly one of our faculties to interact with the environment. Roughly speaking, it is close to the psychologist’s notion of id in distinction to the ego and superego. Level seven is much more extensive than the sixth, the unconscious memory hardly ever forgets, just like a neural net which gobbles tons of input data to modify its state. However memory retrieval here is much harder, if at all possible, compared to the conscious memory.

It is interesting how Henri Poincare, himself a leading scientist and mathematician, describe scientific discovery in one of his books. He said that discovery is often preceded by conscious hard work. The final discovery is however in the domain of unconscious, where all previous work are somehow stirred to produce random combinations, a few of which might actually be a new discovery or a new theorem. The actual verification phase or proof of the theorem is again done in level six.

The awareness of self happens in the sixth as well as the seventh levels of consciousness. The consciousness is within ourselves. In the eighth level, we move to the collective unconscious, a term introduced by C.G. Jung. This is a kind of repository of events, causal happenings that have happened ever since. The term collective unconsciousness is actually not accurate here, since the eight’s level can be both conscious and unconscious. Buddhists call this the alaya consciousness, a repository of all actions, in other words, karma.

Very often in history, we have more than one person making roughly the same discovery at about the same time, independently from each other. It could not be just coincidence, more likely because the discovery was ripe at the time. Zeitgeist is the German word the spirit of the age describing this situation. Taoism has a concept of Wu Wei, or non-action/inaction, relying instead on recognizing and going with the flow.

This eight’s level of consciousness is the unborn consciousness, it is the consciousness which existed before we were born.

Going one step further, we come to the ninth level of consciousness, also called the amala consciousness. It is rather mystical and requires a lot of believing to accept it. If we believe that there is a realm where causality and dualism end, beyond space time and beyond good and evil, then this is it. Some religions have a concept of Emptiness, which is unlike a physical vacuum, devoid of all things, but empty of the self, and contains everything. We must give up the existence of self (there is no self or anatta) in order to reach this level.

Summary

Some memes are like viruses and parasites of the mind. There are no anti-viruses, we can’t just re-format our minds to install a new operating system. Mindfulness is one way to deal with mind viruses, using bare attention and clear comprehension, and generally Insight Meditation, to detach ourselves from them.

This blog is about memes, we have a new theory about memes as classes and patterns with attachments, and about mindfulness as a debugging technique.

A critique of the memetic algorithm

A pseudo-code representation of the algorithm (or one of its variants) is as follows:

1. Start with an initial population
2. Evaluate fitness
3. For each individual do local search for improvement, update fitness
4. Selection of individuals for crossover.
5. Generate new population by genetic operations.
6. repeat step 2

Comparing this with the original genetic algorithm, we see that the only difference is step 3, where a local search is conducted. If we imagine the search landscape as hilly with many local maxima, the local search would most likely find the local optima, and the normal genetic crossover would find new solutions. It is sometimes said that memetic algorithms are hybrid genetic algorithms, combining a population based global search with individual local search.

Computational results indicate a vast improvement relative to genetic algorithms.

Critique of the memetic algorithm.

It is when we look at a memetic algorithm as a kind of model of how memes work, that we find that it doesn’t reflect the idea of memes very well.

Some of the reasons are:

1. MA still works with genes as the sole replicator, memes do not appear in the algorithm at all

2. There is no mechanism how memes are copied from individual to individual, nor how memes are modified and combined to meme plexes

3. There is no global meme pool existing across generations of populations.

4. It is not clear how memes affect the fitness of individuals.

The global meme pool is almost like the pheromones in the ant colony algorithm, except that they can undergo memetic operations and survive generations.

Granted that these points are valid, it remains to be seen whether a “true” memetic algorithm can be devised, which mimics memes better and yet is an improvement of MA in terms of performance. A cursory consideration tells us that such an algorithm will be much more complex than MA, since it would have 2 kinds of replicators, and 2 sets of genetic and memetic operations. Whereas the genes are practically linear in nature, memes have nonlinear structure.

It is probable that the memes in such an algorithm will be domain specific, memes for problem A can be quite different from memes for problem B.

Reference:

P. Moscato, On Evolution, Search, Optimization, Genetic Algorithms and Martial Arts: Towards Memetic Algorithms, Caltech Concurrent Computation Program, C3P Report 826, (1989).


Memetic Algorithms' Home Page

Genetic Algorithms

Genetic algorithms

Computer algorithms often imitate nature. Simulated annealing comes from physics, neural networks and genetic algorithm come from biology. Specifically, genetic algorithm is a simple model of evolution. John Holland in the 1970s wrote a book, and made genetic algorithm widely known, and since then various practical applications have been found in many areas.

The algorithm assumes a set of genes forming chromosomes which uniquely determine individuals of a population. The chromosomes are linear strings of fixed lengths.

The algorithm also requires a fitness function used to evaluate individuals.

A pseudo-code representation of the algorithm (or one of its variants) is as follows:

1. Start with an initial population
2. Evaluate fitness
3. Selection of individuals for genetic operations, such as mutations and crossovers
4. Generate new population by genetic operations.
5. repeat step 2

In practice, the algorithm has a stopping criteria to avoid the unending loop.

The algorithm is basically non-deterministic, firstly in the selection of individuals for genetic oiperations, and in the application of genetic operations. Individuals with a higher fitness will have a higher probability of being selected. The mutation and crossover operations also have probabilities of being selected.

Note that the size of the population is constant, the same number of individuals is generated and deleted in the population.

Holland gave an argument about the efficiency of the algorithm in the form of a “building block hypothesis”.

Variations and extensions of the algorithm exist since the original inception, we mention a few here.

Koza’s genetic programming uses a different data structure instead, namely trees or LISP programs. The individuals are thus programs.

The Genetic Expression Programming (or GEP) was invented by Candida Ferreira. It uses trees encoded as strings. To keep the string length fixed, she introduced non-coding or junk genes.

The compact genetic algorithm does away with the population altogether and replaces it with a probability distribution.

In the next blog, we will consider memetic algorithms

Links:

• Genetic algorithm FAQ
• Source Code and other information
• Genetic Algorithm Books
  
• Genetic Programming Books