subtyping

The concept of " change of perspective " , where a single object is viewed from different angles, each providing a different image (that is a different formal description) but each lacking nothing of the ipseity of the object nor of its essential qualities, has received no formalization so far. In this paper we formalize this concept using identity types in pure intentional type theory and we briefly give the sketch of two of the applications of this formalization in natural language processing and programming languages.

Contracts are behavioral descriptions of Web services. We devise a theory of contracts that formalizes the compatibility of a client with a service, and the safe replacement of a service with another service. The use of contracts statically ensures the successful completion of every possible interaction between compatible clients and services. The technical device that underlies the theory is the filter , which is an explicit coercion preventing some possible behaviors of services and, in doing so, make services compatible with different usage scenarios. We show that filters can be seen as proofs of a sound and complete subcontracting deduction system which simultaneously refines and extends Hennessy's classical axiomatization of the must testing preorder. The relation is decidable, and the decision algorithm is obtained via a cut-elimination process that proves the coherence of subcontracting as a logical system. Despite the richness of the technical development, the resulting ...

While abundant sequence information is available from human immunodeficiency virus type 1 (HIV-1) subtypes A, B, C and CRF01_AE for HIV-1 vaccine design, sequences from West Africa are less represented. We sought to augment our understanding of HIV-1 variants circulating in 6 Nigerian cities as a step to subsequent HIV-1 vaccine development.The G/CRF02_AG multi-region hybridization assay (MHA) was developed to differentiate subtype G, CRF02_AG and their recombinants from other subtypes based on 7 HIV-1 segments. Plasma from 224 HIV-1 infected volunteers enrolled in a cohort examining HIV-1 prevalence, risk factor, and subtype from Makurdi (30), Abuja (18), Enugu (11), Kaduna (12), Tafa (95), and Ojo/Lagos (58) was analyzed using MHA. HIV-1 genomes from 42 samples were sequenced to validate the MHA and fully explore the recombinant structure of G and CRF02_AG variants.The sensitivity and specificity of MHA varied between 73-100% and 90-100%, respectively. The subtype distribution as ...

The object-oriented paradigm is increasingly used in the implementation and the use of web services. However, the mismatch between objects and document structures in the wire has a negative impact over interoperability, more particularly when subtyping is involved. In this paper, we discuss how to improve interoperability in this context by preserving the subsumption property associated to subtyping. First we show the weaknesses

Do voters have the same stereotypes of Black politicians that they have of Black people in general? We argue that common stereotypes of Blacks (e.g., lazy, violent) may not apply to perceptions of Black politicians. Instead, we hypothesize that Black politicians are a unique subtype of the larger group Blacks, different enough to warrant their own stereotypes. We take an inductive approach to understanding the stereotypes of Black politicians. Employing a classic psychology research design (Katz & Braly, 1933) in which respondents list traits for a target group, we find that there is little overlap of stereotype content between Black politicians and Blacks. Our results therefore indicate that Black politicians constitute a separate and unique subtype of Blacks. Our analysis explores similarities and differences between stereotypes of Black politicians and two other groups: Black professionals (another subtype of Blacks) and politicians. We discuss the implications of our findings fo...

Our objective is to provide a model in type theory, using identity types, for parametric polymorphism, subtypes and inheritance. The resulting programming language is a monomor-phic language that has the advantages of polymorphic languages. Since the implementation is using only identity types and since identity types are primitive components of type theory, desirables like type safety, uniqueness of types and the soundness of the system are given at no cost. That is, unlike competing approaches, this way of modeling poly-morphism is not through an extension of the type theory; rather we are using a primitive component of the theory hence no extra work is needed to check whether this new functionality of the system has any side effects on its type safety, uniqueness of types and soundness.

THE HUMAN IMMUNODEFICIENCY VIRUS TYPE 1 (HIV-1) dis-plays a high degree of genetic variability and a number of subtypes or clades are identified. The highest number of HIV-1 subtypes were reported in central Africa where all ma-jor subtypes of groups M (A through K) as ...

Abstract: The object-oriented paradigm is increasingly used in the implementation and the use of web services. How-ever, the mismatch between objects and document structures in the wire has a negative impact over interoper-ability, more particularly when subtyping is involved. In this paper, we discuss how to improve interoperability in this context by preserving the subsumption property associated to subtyping. First we show the weaknesses of existing web service frameworks used for serialization and deserialization. Second we propose new foun-dations for serialization and deserialization, which leads to the specification of a new data binding between objects and document structures, compatible with subtyping. 1

Abstract. We investigate client-server interaction where duties and rights of the parties are asymmetric, in the sense that the client is allowed to abort any session before the server has completed, but not vice versa. This implies that the client can interact with any server offering at least what she is looking for, but possibly more. We formalize such asymmetry in the setting of session types via a form of subtyping in depth, which we call prefix relation. This is apparently conflicting with the rigid duality imposed by session types; nonetheless the resulting system retains all basic correctness properties. Moreover, the system we propose highlights interesting aspects concern-ing the flow of communication inside a session. In particular it reveals that usual subtyping theories cannot be extended by means of prefix, which turns out to be a different concept.

Contracts are behavioral descriptions of Web services. We devise a theory of contracts that formalizes the compatibility of a client with a service, and the safe replacement of a service with another service. The use of contracts statically ensures the successful completion of every possible interaction between compatible clients and services. The technical device that underlies the theory is the filter , which is an explicit coercion preventing some possible behaviors of services and, in doing so, make services compatible with different usage scenarios. We show that filters can be seen as proofs of a sound and complete subcontracting deduction system which simultaneously refines and extends Hennessy's classical axiomatization of the must testing preorder. The relation is decidable, and the decision algorithm is obtained via a cut-elimination process that proves the coherence of subcontracting as a logical system. Despite the richness of the technical development, the resulting ...

Our objective is to provide a model in type theory, using identity types, for parametric polymorphism, subtypes and inheritance. The resulting programming language is a monomor-phic language that has the advantages of polymorphic languages. Since the implementation is using only identity types and since identity types are primitive components of type theory, desirables like type safety, uniqueness of types and the soundness of the system are given at no cost. That is, unlike competing approaches, this way of modeling poly-morphism is not through an extension of the type theory; rather we are using a primitive component of the theory hence no extra work is needed to check whether this new functionality of the system has any side effects on its type safety, uniqueness of types and soundness.