• Title/Summary/Keyword: default rule

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Semantics for Default Rules

  • Yeom, Jae-Il
    • Language and Information
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    • v.4 no.2
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    • pp.69-92
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    • 2000
  • It is well-known that default rules require a nonmonotonic logic. Veltman proposed one dynamic theory which interprets default rules in such a way that correct inferences can be made at each information state. But his theory has some problems. First, this theory excludes the possibility that a default rule can be true of false. Second, his representation of an information state makes it difficult to interpret a default rule embedded in another sentence. Third, the notion of a frame which is introduced in the interpretation of a default rule and the adjustment of inferential expectation has a more complex structure than is necessary, In this paper, I propose a truth-conditional theory of default rules in which the meaning of a default rule is defined as a truth-condition in a possible world and which assumes a simpler structure of a frame. This makes it possible to interpret a default rule embedded in a sentence. A dynamic theory for default rules is also proposed for correct inferences based on default rules.

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A study on the Application of the Contra Proferentem Rule in the Interpretation of Marine Insurance Policies (해상보험증권의 해석상 작성자 불이익의 원칙의 적용에 관한 연구)

  • Seong-Hoo Kim;Nak-Hyun Han
    • Korea Trade Review
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    • v.45 no.5
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    • pp.279-301
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    • 2020
  • In the absence of any guidance under statutory law, such as the Rules for Construction of Policy, MIA 1906, judges should follow the general principles of interpretation that apply to all contracts. In simple terms, Contra Proferentem Rule means that if the contents of the terms and conditions are ambiguous, they are interpreted against the writer of the terms and conditions. In the Anglo-American Contract Law, the 'default rule' is an important judicial tool that can supplement defects in contract norms and reinforce the principle of private autonomy through gap-filling techniques related to the interpretation of contracts. In Korea, it is sometimes mentioned in case of precedent, and it has been established as a clear rule. This study analyzes the interpretation of terms and conditions is not in the form that the interpretation of other general contracts and other interpretation principles are valid, but contracts based on terms and conditions are also contracts, and as a general rule, the interpretation of terms and conditions is explained like the general contract interpretation.

A Nonmonotonic Inheritance Reasoner with Probabilistic Default Rules (확률적 디폴트 규칙들을 이용한 비단조 상속추론 시스템)

  • Lee, Chang-Hwan
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.2
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    • pp.357-366
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    • 1999
  • Inheritance reasoning has been widely used in the area of common sense reasoning in artificial intelligence. Although many inheritance reasoners have been proposed in artificial intelligence literature, most previous reasoning systems are lack of clear semantics, thus sometimes provide anomalous conclusions. In this paper, we describe a set-oriented inheritance reasoner and propose a method of resolving conflicts with clear semantics of defeasible rules. The semantics of default rule is provided by statistical analysis of $\chi$ method, and likelihood of rule is computed based on the evidence in the past. Two basic rules, specificity and generality, are defined to resolve conflicts effectively in the process of reasoning. We show that the mutual tradeoff between specificity and generality 추 prevent many anomalous results from occurring in traditional inheritance reasoners. An algorithm is provided. and some typical examples are given to show how the specificity/generality rules resolve conflicts effectively in inheritance reasoning.

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A Predictive Two-Group Multinormal Classification Rule Accounting for Model Uncertainty

  • Kim, Hea-Jung
    • Journal of the Korean Statistical Society
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    • v.26 no.4
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    • pp.477-491
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    • 1997
  • A new predictive classification rule for assigning future cases into one of two multivariate normal population (with unknown normal mixture model) is considered. The development involves calculation of posterior probability of each possible normal-mixture model via a default Bayesian test criterion, called intrinsic Bayes factor, and suggests predictive distribution for future cases to be classified that accounts for model uncertainty by weighting the effect of each model by its posterior probabiliy. In this paper, our interest is focused on constructing the classification rule that takes care of uncertainty about the types of covariance matrices (homogeneity/heterogeneity) involved in the model. For the constructed rule, a Monte Carlo simulation study demonstrates routine application and notes benefits over traditional predictive calssification rule by Geisser (1982).

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A Bayesian Diagnostic Measure and Stopping Rule for Detecting Influential Observations in Discriminant Analysis

  • Kim, Myung-Cheol;Kim, Hea-Jung
    • Journal of the Korean Statistical Society
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    • v.29 no.3
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    • pp.337-350
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    • 2000
  • This paper suggests a new diagnostic measure and a stopping rule for detecting influential observations in multiple discriminant analysis (MDA). It is developed from a Bayesian point of view using a default Bayes factor obtained from the fractional Bayes factor methodology. The Bayes factor is taken as a discriminatory information in MDA. It is shown that the effect of an observation over the discriminatory information is fully explained by the diagnostic measure. Based on the measure, we suggest a stopping rule for detecting influential observations in a given training sample. As a tool for interpreting the measure a graphical method is sued. Performance of the method is used. Performance of the method is examined through two illustrative examples.

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Internal Legal Relationship Under the Time Charter Party (정기용선계약상 대내적 법률관계)

  • Kim, In Hyeon
    • Journal of Arbitration Studies
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    • v.30 no.4
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    • pp.163-177
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    • 2020
  • There are several ways to implement charter parties in the operation of the vessel. Under the time charter party, the charterer borrows the vessel from the shipowner and uses the vessel to benefit his business. The time charter party's legal relationship can be divided into internal and external relationships. This article deals with an internal relationship. The legal matters between the shipowner and charterer are regulated by the agreement. The NYPE is the most widely circulated type of time charter party. According to the NYPE, navigational matters fall upon the shipowner while business matter falls upon the time charterer. There are vague parts in interpreting NYPE articles. NYPE Art. 8, called the employment clause, is one of them. The Master employed by the shipowner should follow the order of the charterer. Whether the charterer has the right to order the Master of the vessel to follow the navigating route recommended by him was addressed in the Hill Harmony case by the UK Supreme Court. The court was affirmative. Under the Ocean Victory case, whether the time charterer has an obligation to order the Master to go out to escape heavy weather from the berth at the port was at issue. The Japanese lower court decided negatively. There is a tendency that many countries insert default rule in the maritime law to apply it to the case at issue in a case where there is no agreement. It serves the enhancement of legal stability; China, Japan, and Germany are such countries. The author thinks that Korea should follow the above three countries' revision of their maritime law.

A Comparative Analysis regarding Difference of ISP98 and URDG758 (보증신용장통일규칙과 청구보증통일규칙 비교분석)

  • Park, Sae-Woon;Han, Ki-Moon
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.51
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    • pp.263-283
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    • 2011
  • There are two typical international rules in issuing guarantee for obligations of party which is responsible to provide some duties such as services, construction, plants, loan repayment, etc. The two internationally recognized rules are currently ISP98 and URDG758. ISP98 was firstly introduced in 1998 for American banks to issue standby letter of credit domestic and overseas for the area where UCP does not cover. URDG was introduced first in 1991 in the name of URDG458 but it has not been widely used and therefore new URDG named URDG758 came out in 2010 to accommodate more standard guarantee practice. At the face of these two prevailing international rules, the users are sometimes confused which rule would be more suitable for their individual transaction. This led us to conduct a comparative analysis on these two rules. Our study suggests that URDG758 is more adequate for construction, ship-building and plants-supply obligations whilst ISP98 is for financial obligations. Also attentions are required when issues such as counter guarantee, governing rule, presentation period, document examination period and default statement exist. This is because ISP98 and URDG758 have different view points.

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The Prediction of Export Credit Guarantee Accident using Machine Learning (기계학습을 이용한 수출신용보증 사고예측)

  • Cho, Jaeyoung;Joo, Jihwan;Han, Ingoo
    • Journal of Intelligence and Information Systems
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    • v.27 no.1
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    • pp.83-102
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    • 2021
  • The government recently announced various policies for developing big-data and artificial intelligence fields to provide a great opportunity to the public with respect to disclosure of high-quality data within public institutions. KSURE(Korea Trade Insurance Corporation) is a major public institution for financial policy in Korea, and thus the company is strongly committed to backing export companies with various systems. Nevertheless, there are still fewer cases of realized business model based on big-data analyses. In this situation, this paper aims to develop a new business model which can be applied to an ex-ante prediction for the likelihood of the insurance accident of credit guarantee. We utilize internal data from KSURE which supports export companies in Korea and apply machine learning models. Then, we conduct performance comparison among the predictive models including Logistic Regression, Random Forest, XGBoost, LightGBM, and DNN(Deep Neural Network). For decades, many researchers have tried to find better models which can help to predict bankruptcy since the ex-ante prediction is crucial for corporate managers, investors, creditors, and other stakeholders. The development of the prediction for financial distress or bankruptcy was originated from Smith(1930), Fitzpatrick(1932), or Merwin(1942). One of the most famous models is the Altman's Z-score model(Altman, 1968) which was based on the multiple discriminant analysis. This model is widely used in both research and practice by this time. The author suggests the score model that utilizes five key financial ratios to predict the probability of bankruptcy in the next two years. Ohlson(1980) introduces logit model to complement some limitations of previous models. Furthermore, Elmer and Borowski(1988) develop and examine a rule-based, automated system which conducts the financial analysis of savings and loans. Since the 1980s, researchers in Korea have started to examine analyses on the prediction of financial distress or bankruptcy. Kim(1987) analyzes financial ratios and develops the prediction model. Also, Han et al.(1995, 1996, 1997, 2003, 2005, 2006) construct the prediction model using various techniques including artificial neural network. Yang(1996) introduces multiple discriminant analysis and logit model. Besides, Kim and Kim(2001) utilize artificial neural network techniques for ex-ante prediction of insolvent enterprises. After that, many scholars have been trying to predict financial distress or bankruptcy more precisely based on diverse models such as Random Forest or SVM. One major distinction of our research from the previous research is that we focus on examining the predicted probability of default for each sample case, not only on investigating the classification accuracy of each model for the entire sample. Most predictive models in this paper show that the level of the accuracy of classification is about 70% based on the entire sample. To be specific, LightGBM model shows the highest accuracy of 71.1% and Logit model indicates the lowest accuracy of 69%. However, we confirm that there are open to multiple interpretations. In the context of the business, we have to put more emphasis on efforts to minimize type 2 error which causes more harmful operating losses for the guaranty company. Thus, we also compare the classification accuracy by splitting predicted probability of the default into ten equal intervals. When we examine the classification accuracy for each interval, Logit model has the highest accuracy of 100% for 0~10% of the predicted probability of the default, however, Logit model has a relatively lower accuracy of 61.5% for 90~100% of the predicted probability of the default. On the other hand, Random Forest, XGBoost, LightGBM, and DNN indicate more desirable results since they indicate a higher level of accuracy for both 0~10% and 90~100% of the predicted probability of the default but have a lower level of accuracy around 50% of the predicted probability of the default. When it comes to the distribution of samples for each predicted probability of the default, both LightGBM and XGBoost models have a relatively large number of samples for both 0~10% and 90~100% of the predicted probability of the default. Although Random Forest model has an advantage with regard to the perspective of classification accuracy with small number of cases, LightGBM or XGBoost could become a more desirable model since they classify large number of cases into the two extreme intervals of the predicted probability of the default, even allowing for their relatively low classification accuracy. Considering the importance of type 2 error and total prediction accuracy, XGBoost and DNN show superior performance. Next, Random Forest and LightGBM show good results, but logistic regression shows the worst performance. However, each predictive model has a comparative advantage in terms of various evaluation standards. For instance, Random Forest model shows almost 100% accuracy for samples which are expected to have a high level of the probability of default. Collectively, we can construct more comprehensive ensemble models which contain multiple classification machine learning models and conduct majority voting for maximizing its overall performance.

Semantics of Prioritized Default Rule System (우선순위 디폴트 규칙 시스템의 의미론)

  • 유희준;배민오;최진영
    • Proceedings of the Korean Information Science Society Conference
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    • 2003.10a
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    • pp.241-243
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    • 2003
  • 지능형 정보 에이전트 시스템에서 사용되는 디폴트 규칙 시스템의 결론 집합을 생성하기 위한 추론 과정에서 불일치를 발생할 수 있는 새로운 오순 상황을 제시하고, 이를 해결할 수 있는 새로운 의미론을 정의한다. 확장 논리 프로그램은 추론된 결과 집합에서 같은 심벌이 양의 부호와 음의 부호를 동시에 가진 형태로 존재하는 경우에 모순이 발생하게 된다. 막장 논리 프로그램에 기반을 둔 디폴트 추론 시스템에서도 이런 모순을 가지게 되며, 이 문제를 해결하기 위한 방법이 정의되어 있다. 하지만, 비단조 추론을 하는 디폴트 규칙 시스템에서는 이런 문제 외에도 모순이 발생하게 된다. 하지만, 기존의 연구에서는 이러한 문제를 해결하는 방범이 고려되지 않았다. 최근에 들어서 디폴트 규칙 시스템은 지능형 에이전트에 내재되면서 에이전트간의 협상과 업데이트 등에 많이 사용되고 있다. 만일, 에이전트 내에서 규칙 시스템이 모순 상황이 발생하는 경우 예기치 않은 손실이 발생하게 된다. 따라서 결론 집합을 일관성 있게 추론하는 것은 지능형 에이전트 시스템의 신뢰성을 높이기 위해서 반드시 필요한 사항이다. 더욱이 에이전트 시스템의 사용분야가 지속적으로 늘어나는 상황에서 기존에 제안된 모순 이외에 각 분야에서 특성에 따라서 발생 가능한 모순이 발생하게 되며, 이 문제를 해결하는 것이 중요한 문제이다. 본 논문에서는 기존에 정의된 모순 외에 발생 가능한 문제점을 제시하고 이를 해결하기 위한 새로운 규칙 시스템의 의미론을 정의하였다.

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Data-Dependent Choice of Optimal Number of Lags in Variogram Estimation

  • Choi, Seung-Bae;Kang, Chang-Wan;Cho, Jang-Sik
    • The Korean Journal of Applied Statistics
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    • v.23 no.3
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    • pp.609-619
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    • 2010
  • Geostatistical data among spatial data is analyzed in three stages: (1) variogram estimation, (2) model fitting for the estimated variograms and (3) spatial prediction using the fitted variogram model. It is very important to estimate the variograms properly as the first stage(i.e., variogram estimation) affects the next two stages. In general, the variogram is estimated with the moment estimator. To estimate the variogram, we have to decide the 'lag increment' or the 'number of lags'. However, there is no established rule for selecting the number of lags in estimating the variogram. The present paper proposes a method of choosing the optimal number of lags based on the PRESS statistic. To show the usefulness of the proposed method, we perform a small simulation study and show an empirical example with with air pollution data from Korea.