On the tree-transformation power of XSLT

XSLT is a standard rule-based programming language for expressing transformations of XML data. The language is currently in transition from version 1.0 to 2.0. In order to understand the computational consequences of this transition, we restrict XSLT to its pure tree-transformation capabilities. Under this focus, we observe that XSLT~1.0 was not yet a computationally complete tree-transformation language: every 1.0 program can be implemented in exponential time. A crucial new feature of version~2.0, however, which allows nodesets over temporary trees, yields completeness. We provide a formal operational semantics for XSLT programs, and establish confluence for this semantics

On Functionality of Visibly Pushdown Transducers

Visibly pushdown transducers form a subclass of pushdown transducers that (strictly) extends finite state transducers with a stack. Like visibly pushdown automata, the input symbols determine the stack operations. In this paper, we prove that functionality is decidable in PSpace for visibly pushdown transducers. The proof is done via a pumping argument: if a word with two outputs has a sufficiently large nesting depth, there exists a nested word with two outputs whose nesting depth is strictly smaller. The proof uses technics of word combinatorics. As a consequence of decidability of functionality, we also show that equivalence of functional visibly pushdown transducers is Exptime-Complete.Comment: 20 page

XML type checking with macro tree transducers

The tree transformation language tl is introduced which incorporates full MSO-pattern-matching, arbitrary navigation through the input, and named procedures with accumulating parameters. Thus, tl essentially captures all features offered by existing document processing languages such as Xslt, fxt, or XDuce. It is proved that tl, despite its expressiveness, still allows for effective inverse type inference. This result is obtained by means of a translation of tl transformers into compositions of (stay) macro tree transducers

XML Type Checking with Macro Tree Transducers

MSO logic on unranked trees has been identified as a convenient theoretical framework for reasoning about expressiveness and implementations of practical XML query languages. As a corresponding theoretical foundation of XML transformation languages, the “transformation language ” TL is proposed. This language is based on the “document transformation language” DTL of Maneth and Neven which incorporates full MSO pattern matching, arbitrary navigation in the input tree using also MSO patterns, and named procedures. The new language generalizes DTL by additionally allowing procedures to accumulate intermediate results in parameters. It is proved that TL – and thus in particular DTL – despite their expressiveness still allow for effective inverse type inference. This result is obtained by means of a translation of TL programs into compositions of top-down finite state tree transductions with parameters, also called (stay) macro tree transducers

Differential T cell responses to Mycobacterium tuberculosis ESAT6 in tuberculosis patients and healthy donors

Vaccination against and diagnosis of tuberculosis are still insufficient. Proteins secreted by Mycobacterium tuberculosis induce strong immune responses in tuberculosis and constitute prime candidates for development of novel vaccines against tuberculosis as well as for immunodiagnostic assays. We investigated the role of the secreted proteins MPT63, MPT64 and ESAT6 from M. tuberculosis in healthy individuals and tuberculosis patients. None of the secreted proteins stimulated peripheral blood mononuclear cells from healthy donors. In contrast, CD4+ T cells from many tuberculosis patients were stimulated in an MHC class II-restricted fashion by ESAT6, but not by MPT63 or MPT64. T cell reactivities of tuberculosis patients were focused on the N-terminal region of ESAT6. The ESAT6 T cell epitopes were presented by different HLA-DR phenotypes. Cell cultures responding to either ESAT6 or synthetic peptides thereof showed mRNA transcripts for macrophage inflammatory protein (MIP)-1alpha, monocyte chemotactic protein (MCP)-1 or IL-8 and production of IFN-gamma and MIP-1alpha. Our results suggest that the secreted M. tuberculosis proteins MPT63, MPT64 or ESAT6 do not stimulate unprimed T cells, and that ESAT6 may be a potential candidate antigen for detection of clinical disease

Visibly pushdown transducers with look-ahead

Visibly Pushdown Transducers (VPT) form a subclass of pushdown transducers. In this paper, we investigate the extension of VPT with visibly pushdown look-ahead (VPT la). Their transitions are guarded by visibly pushdown automata that can check whether the well-nested subword starting at the current position belongs to the language they define. First, we show that VPT la are not more expressive than VPT, but are exponentially more succinct. Second, we show that the class of deterministic VPT la corresponds exactly to the class of functional VPT, yielding a simple characterization of functional VPT. Finally, we show that while VPT la are exponentially more succinct than VPT, checking equivalence of functional VPT la is, as for VPT, ExpT-C. As a consequence, we show that any functional VPT is equivalent to an unambiguous one. © 2012 Springer-Verlag.SCOPUS: cp.kinfo:eu-repo/semantics/publishe

A pushdown machine for recursive XML processing

Abstract. XML transformations are most naturally defined as recursive functions on trees. Their direct implementation, however, causes inefficient memory usage because the input XML tree is completely built in memory before being processed. In contrast, programs in stream processing style minimise memory usage since it may effectively release the memory occupied by a prefix of the input not needed by the computation. Stream processing programs, however, are harder to write because the programmer is left with the burden to maintain the state. In this paper, we propose a model for XML stream processing and show that all programs written in a particular style of recursive functions on XML trees, the macro forest transducer, can be automatically translated to our stream processors. The stream processor is declarative in style, but can be implemented efficiently by a pushdown machine. We thus get the best of both worlds — program clarity, and efficiency in execution.