Browsing by Subject "Text processing (Computer science)."
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Item Open Access Parallel text retrieval on temporally versioned document collections(2008) Gür, ÖzlemIn recent years, as the access to the Internet is getting easier and cheaper, the amount and the rate of change of the online data presented to the Internet users are increasing at an astonishing rate. This ever-changing nature of the Internet causes an ever-decaying and replenishing information collection where newly presented data generally replaces old and sometimes valuable data. There are many recent studies aiming to preserve this valuable temporal data and size and number of temporal Web data collections are increasing. We believe that soon, information retrieval systems responding to time-range queries in a reasonable amount of time will emerge as a means of accessing vast temporal Web data collections. Due to tremendous size of temporal data and excessive number of query submissions per unit time, temporal information retrieval systems will have to utilize parallelism as much as possible. In parallel systems, in order to index collections using inverted indices, a strategy on distribution of the inverted indices has to be followed. In this study, the feasibility of time-based partitioned versus term-based partitioned temporalweb inverted-indices is analyzed and a novel parallel text retrieval system for answering temporal web queries is implemented considering the number of queries processed in unit time. Moreover, we investigate the performance of skip-list based and randomized-select based ranking schemes on time-based and termbased partitioned inverted indexes. Finally, we compare time-balanced and sizebalanced time-based partitioning schemes. The experimental results at small to medium number of processors reveal that for medium to long length queries time-based partitioning works better.Item Open Access Performance comparison of query evaluation techniques in parallel text retrieval systems(2008) Tokuç, A. AylinToday’s state-of-the-art search engines utilize the inverted index data structure for fast text retrieval on large document collections. To parallelize the retrieval process, the inverted index should be distributed among multiple index servers. Generally the distribution of the inverted index is done in either a term-based or a document-based fashion. The performances of both schemes depend on the total number of disk accesses and the total volume of communication in the system. The classical approach for both distributions is to use the Central Broker Query Evaluation Scheme (CB) for parallel text retrieval. It is known that in this approach the central broker is heavily loaded and becomes a bottleneck. Recently, an alternative query evaluation technique, named Pipelined Query Evaluation Scheme (PPL), has been proposed to alleviate this problem by performing the merge operation on the index servers. In this study, we analyze the scalability and relative performances of the CB and PPL under various query loads to report the benefits and drawbacks of each method.Item Open Access A performatory analysis of the overt use of the predicate "true"(2013) Şenol, Mahmut BurakThe de ationary theory has been one of the most in uential theories of truth in contemporary philosophy. This theory holds that there is no property of truth at all, and that overt uses of the predicate \true" in our sentences are redundant, having absolutely no e ect on what we express. However, all hypothetical examples used by de ationary theorists in exemplifying the theory, in papers, books, have been taken out of context. Thus, there is no way to examine and analyze what the predicate adds to the sentence within context. We oppose this theory not on philosophical grounds, but on empirical grounds, with an \ordinary language philosophy" approach. We computationally collect 7610 occurrences of overt uses of the predicate \true" in the form \it is true that", from 10 in uential periodicals (newspapers and a magazine) published in the United States. We classify and annotate these examples with respect to coordinating and subordinating conjunctions' positions they contain. We investigate contextual relations of the proposition following the phrase \it is true that" with its surrounding propositions. We encounter 34 di erent syntactical patterns. We propose that in some occurrences of overt uses of the predicate \true", existence of the predicate makes an emphasis, performs an action in the same manner as a performatory verb does. We provide ordinary language appearances of overt uses of the predicate \true", which have been used in linguistically reliable media and constitute pragmatic `counter-examples' to the de ationary theory of truth.Item Open Access Tagging and morphological disambiguation of Turkish text(1994) Kuruöz, İlkerA part-of-speech (POS) tagger is a system that uses various sources of information to assign possibly unique POS to words. Automatic text tagging is an important component in higher level analysis of text corpora. Its output can also be used in many natural language processing applications. In languages like Turkish or Finnish, with agglutinative morphology, morphological disambiguation is a very crucial process in tagging as the structures of many lexical forms are morphologically ambiguous. This thesis present a POS tagger for Turkish text based on a full-scale two-level specification of Turkish morphology. The tagger is augmented with a multi-word and idiomatic construct recognizer, and most importantly morphological disambiguator based on local lexical neighborhood constraints, heuristics and limited amount of statistical information. The tagger also has additional functionality for statistics compilation and fine tuning of the morphological analyzer, such as logging erroneous morphological parses, commonly used roots, etc. Test results indicate that the tagger can tag about 97/% to 99% of the texts accurately with very minimal user intervention. Furthermore for sentences morphologically disambiguated with the tagger, an LFG parser developed for Turkish, on the average, generates 50% less ambiguous parses almost 2.5 times faster.Item Open Access Turkish text generation with systemic-functional grammar(1996) Korkmaz, TurgayNatural Language Generation (NLG) is roughly decomposed into two stages: text planning, and text generation. In the text planning stage, the semantic description of the text is produced from the conceptual inputs. Then, the text generation system transforms this semantic description into an actual text. This thesis focuses on the design and implementation of a Turkish text generation system rather than text planning. To develop a text generator, we need a linguistic theory that describes the resources of the desired natural language, and also a software tool that represents and performs these linguistic resources in a computational environment. In this thesis, in order to carry out the mentioned requirements, we have used a functional linguistic theory called Systemic-Functional Grammar (SFG), and the FUF text generation system as a software tool. The ultimate text generation system takes the semantic description of the text sentence by sentence, and then produces a morphological description for each lexical constituent of the sentence. The morphological descriptions are worded by a Turkish morphological generator. Because of our concentration on the text generation, we have not considered the details of the text planning. Hence, we assume that the semantic description of the text is produced and lexicalized by an application (currently given by hand).