Natural language as an example of a structural system is compared to programming language as a constructive system through analysis of how differently humans and computers process self-reference. An alternative handling of the halting problem in computer systems holds the key to a more natural computer environment and enables a greater understanding of human thought.
In this article, sign and language systems are analyzed from the viewpoint of reflexivity — a system's ability to reinterpret its own output. Human and natural sign systems are reflexive, so this feature has not become an issue in the domain of semiotics. In contrast, not all computer language systems are reflexive, and analysis shows that there are degrees of reflexivity. The history of computer language systems can therefore be regarded as a journey to discover ways of exploiting the reflexivity inherent in each language system to make it more dynamic and self-augmenting. This article examines various computer language systems from the viewpoint of reflexivity and compares this feature with the same feature in human systems.
We examine lambda calculus as a sign system and show that it explains important properties of language. First, we verify that a lambda-term has two essential functionalities of signs — articulation and naming — and argue that a lambda-term can thus be regarded as a sign model. Then, when signs are defined by self-reference, we show that these two functionalities become tightly coupled and that dyadic/triadic sign models become equivalent. Last, we show that the difference of structuralism is explained in relation to the undecidability of the equivalence of two arbitrary lambda-terms.
The correspondence between the triadic sign model proposed by Peirce and the dyadic sign model proposed by Saussure is examined. Traditionally, it has been thought that Peirce's interpretant corresponds to Saussure's signified and Saussure's model lacks Peirce's object. However, our analysis of the two most widely used computer programming paradigms suggests that Peirce's object formally corresponds to Saussure's signified, and that Saussure's sign model is obtained when Peirce's interpretant is located outside of his model in the language system.
This article examines the concept of void with the question of whether the concept forms a sign. A void in this article is defined as a spatio-temporal empty space existing in a representation. The aim of the analysis is to consider the hidden nature of signs, which cannot be highlighted only through an analysis of typical signs within social convention. As a semiotic tool to conduct the discussion, the notion of a zero sign of Lévi-Strauss is introduced. The article considers all possible zeros that can exist within the Saussurian sign model and introduces three cases: an omitted sign, an ambiguous signified, and an ambiguous sign. After examining the features of each kind, the concept of void is considered in these terms, with the conclusion that it belongs to the ambiguous sign case. Analysis of void with respect to the zero sign highlights the nature of signs as being reflexive, holistic and speculative. Because the signifier is barely delimited, it influences the surrounding sign systems, including the one existing at the meta-level. An ambiguous sign is deemed to allow for concept sharing among people even when the signifier and the signified remain ambiguous.
We discuss how Hjelmslev's denotation, connotation, and metasign could correspond to Peirce's icon, index, and symbol. Our argument is based on the application of both theories to the programming language problem of confusion as to whether a sign signifies a value, reference, or type.
We argue that the essence of thirdness in computing is self-reference. Our discussion is grounded on the theories of Church and Curry, which have been studied in the domain of theoretical computing. Using their theories, we show that any program can be transformed into a program consisting only of three-term relations, where the essence of the three-term relations lies in self-reference.
Heart-type fatty acid-binding protein (H-FABP) is a low molecular weight cytoplasmic protein and present abundantly in the myocardium. When the myocardium is injured, as in the case of myocardial infarction, low molecular weight cytoplasmic proteins including H-FABP are released into the circulation and H-FABP is detectable in a blood sample. We have already developed a direct sandwich-ELISA for quantification of human H-FABP using two distinct types of monoclonal antibodies specific for human H-FABP. In this study we investigated the clinical validity of H-FABP as a biochemical diagnostic marker in the early phase of acute myocardial infarction (AMI). To evaluate the diagnostic usefulness of H-FABP in the early phase of AMI, blood samples were obtained from the following patients within 12 hours after the appearance of symptoms, and serum levels of H-FABP were compared with those of conventional diagnostic markers, such as myoglobin and creatine kinase isoenzyme MB (CK-MB). Blood samples were collected from patients with confirmed AMI (n=140), patients with chest pain who were afterwards not classified as AMI by normal CK-MB levels (non-AMI) (n=49) and normal healthy volunteers (n=75). The serum concentration of H-FABP was quantified with our direct sandwich-ELISA. The concentration of myoglobin mass was measured with a commercial RIA kit. The serum CK-MB activity was determined with an immuno-inhibition assay kit. The overall sensitivity of H-FA B P, within 12 hours after the appearance of symptoms, was 92.9%, while it was 88.6% with myoglobin and 18.6% with CK-MB. The overall specificity of H-FABP was 67.3%, while it was 57.1% with myoglobin and 98.0% with CK-MB. The diagnostic efficacy rates with these markers were 86.2% (H-FABP), 80.4% (myoglobin) and 39.2% (CK-MB), respectively. The diagnostic validity of H-FABP was further assessed by receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) of H-FABP was 0.921, which was significantly greater than with myoglobin (AUC: 0.843) and CK-MB (AUC: 0.654). These parameters, such as sensitivity, specificity, diagnostic efficacy and diagnostic accuracy, obtained for patients with chest pain within 3 hours and/or 6 hours after the onset of symptoms were almost the same as those for patients within 12 hours after symptoms. H-FABP is more sensitive than both myoglobin and CK-MB, more specific than myoglobin for detecting AMI within 12 hours after the onset of symptoms, and shows the highest values for both diagnostic efficacy and ROC curve analysis. Thus, H-FABP has great potential as an excellent biochemical cardiac marker for the diagnosis of AMI in the early phase.