The previous column story told ( No.20 Weak Classifier and Strong Classifier) how integrated multiple weak classifiers reorganize themselves into a strong and flexible classifier.
Traditionally, engineers merely focused on specific targets that were easy to describe with numbers or were repeatedly observable. If, however, the target is not observable, or difficult to observe, how do we define the target? This time we focus on a conceptual or historical target whose description is often incomplete or observable only once. Even using this fuzzy target, you may notice that the concept of weak classifiers is a powerful framework.
We will first try to select a person with good personality using weak classifiers. Traditional methodology requires that "good personality" be defined, which is not easy. Without defining the object, it is difficult to design the classifier. However, if we can divide the feature into partial sub-features, the classification process becomes easier to manage. The features of a good personality could be expressed as a person who (1) has no biased opinions, (2) regards himself/herself equally with others, (3) does not impose on others, (4) is a good listener, (5) maintains temperate behavior, (6) is not offensive to others. None of these features is strong enough to describe a good personality by itself, but taken together, the extracted personality is expected to be something close. To be stable, each classifier should be independent. By integrating these weak classifiers, a high performance classifier system can be obtained. The individual weak classifiers can be used with the simple logic "if A, then B". Figure 1 shows the relationships between individual statements and the resulting statement, where the central common area represents the logical statement satisfied by all weak conditions. Figure 2 is another diagram of the common region satisfied by all the independent conditions: α, β, γ. The person who passes all tests from (1) to (6) should be a good person.
Fig. 1. Areas A-E depict the logical regions on which many weak pieces
of evidence stand. The center is the common area.
Fig. 2. The cube represents an area that has common but independent
properties, α, β and γ.
According to a theorem of logic, the statement "if not B, then not A" is always correct "if A, then B" is correct. This theorem is called contraposition. Even when the classifier is weak, this classifier should be valid. To check the validity of the weak classifiers, the contraposition theorem is helpful. It is a good idea to test this contraposition before accepting the statement that (1) "a not non-biased person does not always have a good personality."
The deduction, based on weak but many pieces of evidence has been used for many years in the field of history or anthropology. For example, mythology is thought to be man-made fiction with no realistic background, because it starts from God. However, it is unrealistic to believe that a story can be created without any background. If the story is shared by groups of people, it is more reasonable to guess that the story may have some common historical background. Here, I present one example of a folk tale inherited by the local people where I was born.
I was born in the area called Kibi, located in the western part of Japan. Soja is the current dominant city in this part of Okayama prefecture. A large fortress ruins, a few kilometers in size, called Kino Jo (devil's fortress), boasts the following folk tale:
Here is my hypothesis; " The Devil Prince was a leader of a group that immigrated from Kudara."
Following is a list of historical facts and findings.
The large scale Kino Jo, which has never appeared in historical literature, exhibits many of the facts listed above. Combined with historical tales of that era, here is my story of Kino Jo:
The ancient state of Kudara was born with its innovative technology of iron furnaces. After several hundreds of years, the iron ore ran out. With the superior technology of iron furnaces, the population immigrated to western Japan, where they built a strong and wealthy community that sometimes competed with the Japanese government. Kino Jo was the headquarters of the community.
I once asked an acquaintance, "Mr. Kudara, are you a descendant from the kingdom of the Kudara royal family?", His answer was "Yes, I am."
I was deeply impressed by the book Seven Daughters of Eve written by Bryan Sykes. My wife sent our tissue samples to Oxford Ancestors to have our mitochondrial DNA analyzed. Here is one result of the analysis, which tells a very interesting story of my wife's ancestor Sachi.
As the story reveals, most Japanese today may have an ancestral connection with the mainland if we look back 2000 years. During its long history, several waves of immigrants groups with different cultural backgrounds arrived on Japan shores. One of the groups may be the Kudara group, who settled around Kino Jo.
What do you think?