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(No.21) Weak Classifiers with Strong Logic

Classification of Non-rigid Objectives

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."

Application to Historical Interpretation

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:

  1. The group was led by a prince of Kudara, an ancient state in the south of the Korean Peninsula. His wife was princess Azo.
  2. The Prince lived in Kino Jo and annoyed nearby people with criminal acts, who gave him the name Devil Prince.
  3. The Government decided to send troops, led by general Kibitsuhiko, to conquer the Devil Prince.
  4. After many difficulties, Kibitsuhiko finally won the battle.

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.

  1. The shrine called Kibitsu Jinja enshrines Kibitsuhiko, and keeps the tradition of the prophecy using the Devil's kettle. This job is done by females from nearby Azo village, located at the foot of Kino Jo.
  2. The state of Kudara existed from the 4th century to the 7th century in the southern part of the Korean Peninsula. It was crushed just after the allied forces of Kudara & Japan were defeated by the allied forces of Tang & Shilla in 660 AD.
  3. When Kudara was crushed, many people, including royal families, immigrated to Japan.
  4. Kudara's main business was thought to be iron related.
  5. Around the 7th century, iron ore around Kudara was depleted.
  6. Large scale iron production in Japan started in the Chugoku region; as a result much waste was dumped in the Seto inland sea, where the white shoreline became a symbol of Seto sea scenery. Later, the iron production area moved to the north, where much sand flooded the shoreline of the Japan Sea, creating the unique scenery of sand dunes and sandbars.
  7. Today, the remains of many iron furnaces dating back to the 6th and 7th century can be found around Azo, as well as many 5th century Korean style ceramics.
  8. Ruins of the Kino Jo fortress are a constant reminder of ancient Korean style design.
  9. Ancient Japanese poems often have the prologue, magane fuku, meaning iron furnacing, followed by the region Kibi.

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.

Sachi: the great great godmother
Your DNA sequence, which is very rare among native Europeans, is found Predominantly in East Eurasia and the Americas. You are a direct maternal descendant of Sachi, the most frequently encountered clan in Japan.
Sachi's descendants are found throughout Japan today, from Hokkaido in the north to Okinawa in the south. They probably first arrived early in the history of Japan, crossing from the Asian mainland about 12,000 years ago, but later migrations, for example those associated with the Yayoi culture, would also have included other descendants of Sachi.
Sachi's descendants have also been found in mainland Asia (Siberia, China, Taiwan, Korea, Vietnam and Thailand) and in both North and South America. Very occasionally her clan can be found in Europe. Her descendants reached the islands of the Philippines and Indonesia, from where they set sail to Madagascar. Further out into the Pacific, Sachi's descendants are found in Fiji and the islands of Micronesia.
From the features of this geographical distribution of her descendants we believe that Sachi herself lived in Central Asia, probably at least 20,000 years ago. We will become more certain of this as more research is done in the countries of Asia, including Japan.
Thank you for your custom and congratulations on finding your place on the world's largest family tree.
--- Oxford Ancestors ---

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?

(Ej, 2007.02)