My reseach topics are:

- Data Mining
- Inductive Logic Programming
- Algorithmic/Computational Learning Theory
- Comutational Logic
- Abduction

To paper's page

To Hirata's Homepage

(*References*)

- Kouichi Hirata, Ryosuke Nagazumu, Masateru Harao :

**Extraction of Coverings as Monotone DNF Formulas**

*Proc. 6th International Conference on Discovery Science*

Lecture Notes in Artificial Intelligence, 2003 (to appear).

(*References*)

- Kouichi Hirata :

**On Condensation of a Clause**

*Proc. 13th International Conference on Inductive Logic Programming*

Lecture Notes in Artificial Intelligence, 2003 (to appear). - Kouichi Hirata :

**On the Hardness of Learning Acyclic Conjunctive Queries**

*Proc. 11th International Conference on Algorithmic Learning Theory*

Lecture Notes in Artificial Intelligence 1968, 238--251, 2000. - Akihiro Yamamoto, Hiroki Arimura and Kouichi Hirata:

**Inductive Logic Programming and Proof Completion**

Shinichi Morishita, Satoru Miyano (eds.):

*Discovery Science and Data Mining,*Kyoritsu Shuppan, 34--44 (Chapter 4), 2000 (in Japansese). - Kouichi Hirata :

**Flattening and Implication**

*Proc. 10th International Conference on Algorithmic Learning Theory*

Lecture Notes in Artificial Intelligence 1720, 157--168, 1999. - Hiroki Arimura and Kouichi Hirata :

**Learning of First-Order Formulas and Inductive Logic Programming**

*Journal of Japanese Society for Artificial Intelligence*14, 790--799, 1999 (in Japanese).

(*References*)

- Hiroshi Sakamoto, Kouichi Hirata and Hiroki Arimura:

**Learning Elementary Formal Systems with Queries**

*Theoretical Computer Science*298, 21--50, 2003. - Eiju Hirowatari, Kouichi Hirata, Tetsuhiro Miyahara and Setsuo Arikawa:

**Criteria for Inductive Inference with Mind Changes and Anomalies of Recursive Real-Valued Functions**

*The Transaction of IEICE*E-86-D, 219--227, 2003. - Kouichi Hirata and Hiroshi Sakamoto:

**Prediction-Preserving Reducibility with Membership Queries on Formal Languages**

*Proc. 13th International Symposium on Fundamentals of Computation Theory*

Lecture Notes in Computer Science 2138, 172--183, 2001. - Noriko Sugimoto, Takashi Toyoshima, Shinichi Shimozono and Kouichi Hirata :

**A Constructive Learning of Context-Free Languages with a Subpansive Tree**

*Proc. 5th International Colloquium on Grammatical Inference*

Lecture Notes in Artificial Intelligence 1891, 270--283, 2000.

(*References*)

- Kouichi Hirata, Keizo Yamada and Masateru Harao:

**Tractable and Intractable Second-Order Matching Problems**

*Journal of Symbolic Computation*, 37/5, 611-628, 2004.

(A preliminary version has been appeared in COCOON'99.) - Kengo Kubo, Keizo Yamada, Kouichi Hirata, Masateru Harao:

**Efficient Schema Matching Algorithm Based on Pre-Checking**

*The Transaction of IEICE*J85-D-I, 143--151, 2002 (in Japanese). - Keizo Yamada, Kouichi Hirata and Masateru Harao:

**Second-Order Schema Matching Based on Projection Point Labeling**

*Proc. 15th International Workshop on Unification*(UNIF2001),

Technical Report DII 09/01, Dipartimento di Ingegneria dell'Informazione, Universita degli Studi di Siena, 49--53, 2001. - Keizo Yamada, Kouichi Hirata, Masateru Harao:

**Schema Matching and Its Complexity**

*The Transaction of IEICE*J82-D-I, 1307--1316, 1999 (in Japanese). - Shinichi Shimozono, Kouichi Hirata and
Ayumi Shinohara:

**On the Hardness of Approximating the Minimum Consistent Acyclic DFA and Decision Diagram**

*Information Processing Letters*66, 165--170, 1998.

In order to capture the nature of inference, a philosopher Peirce classified inference into three fundamental kinds: deduction, induction, and abduction. In this classification, which based on the form of syllogisms, abduction is characterized as the inference of a case A from a rule A->C and a result C.

Furthermore,
he also placed these three kinds of inference
at each stage of scientific inquiry.
According to him,
every scientific inquiry begins with an observation
of a surprising fact.
The first stage, abduction, of scientific inquiry
proposes a hypothesis
to explain why the fact arises.
The second stage, deduction, derives
new conclusions from the hypothesis.
The third stage, induction,
tests empirically
or corroborates the hypothesis and
the conclusions.
Hence, abduction is not only a kind of inference,
but also a method of scientific discovery.
The inference schema of abduction as the first stage of
scientific inquiry is described in
the following three steps:

- A surprising fact C is observed.
- If A were true, then C would be a matter of course.
- Hence, there is reason to suspect that A is true.

Examples of abduction in literature

(*References*)

- Kouichi Hirata :

**Rule-Generating Abduction for Recursive Prolog**

*Informatica*20, 43--56, 1996. - Kouichi Hirata :

**A Classification of Abduction: Abduction for Logic Programming**

*Machine Intelligence*14, 397--424, 1995.