Schema-aware Extended Annotation Graphs

Abstract

International audienceMultistructured (M-S) documents were introduced as an answer to the need of ever more expressive data models for scholarly annotation, as experienced in the frame of Digital Humanities. Many proposals go beyond XML, that is the gold standard for annotation, and allow the expression of multilevel, concurrent annotation. However, most of them lack support for algorithmic tasks like validation and querying, despite those being central in most of their application contexts. In this paper, we focus on two aspects of annotation: data model expressiveness and validation. We introduce extended Annotation Graphs (eAG), a highly expressive graph-based data model, fit for the enrichment of multimedia resources. Regarding validation ofM-S documents, we identify algorithmic complexity as a limiting factor. We advocate that this limitation may be bypassed provided validation can be checked by construction, that is by constraining the shape of data during its very manufacture. So far as we know, no existing validation mechanism for graph-structured data meets this goal. We define here such a mechanism, based on the simulation relation, somehow following a track initiated in Dataguides. We prove that thanks to this mechanism, the validity of M-S data regarding a given schema can be guaranteed without any algorithmic chec

TAGML: A markup language of many dimensions

“…Extended Annotation Graphs (eAG) [2] is a schema-aware, stando markup model. Following [4], it is based upon the notion of chronology.…”

“…otes necessarily result in cyclic graphs [2] (see p. 7); yet, they too are handled by SeAG schemas. Apart from the expressive power of this syntax (illustrated below), the eAG model bene ts from a schema language (SeAG) that manages multistructured, overlapping, cyclic annotation.…”

“…Apart from the expressive power of this syntax (illustrated below), the eAG model bene ts from a schema language (SeAG) that manages multistructured, overlapping, cyclic annotation. SeAG validation relies upon the notion of rooted simulation 2 [2]. Intuitively, the existence of a simulation of an eAG I S by a schema S implies that all the paths of I S starting at its root have a corresponding path in S, whose label sequence is identical.…”

“…e problem is we cannot, in the absolute, prefer one eAG over the others, since all of them do represent the fact the LeAG document contains two A elements in a row -and also, and most importantly, because the di erent eAG will not be validated against the same schemas. Indeed, considering the three SeAGs below, the above eAG [1] is validated by the schema [S 1 ] only, [2] Choosing one solution against the others thus cannot be done but by considering a prede ned schema. Hence parsing a LeAG means: given a SeAG, yielding a valid eAG that 'represents well' the LeAG -if such an eAG exists.…”

“…Yet, acyclic models, if they do allow multilayer annotation, exhibit the same weakness as XML regarding the representation (and hence, the validation) of non-structural relations between elements; cyclic data models, that rely upon RDF, do not bene t from an e cient validation mechanism yet [29,30]. In a former paper [2], we introduced extended Annotation Graphs (eAG), a cyclic-graph data model experimenting the simulation relation [19] as a validation mechanism. An interesting aspect of simulation is, as we evidenced, that it can be guaranteed by construction, enabling to validate cyclic, multistructured data on the y, just like when using grammar-based validators for XML.…”