Let interrogativo represent an unknown document and let y represent a random target author’s stylistic ‘profile’. During one hundred iterations, it will randomly select (a) fifty per cent of the available stylistic features available (anche.g. word frequencies) and (b) thirty distractor authors, or ‘impostors’ from verso pool of similar texts. Con each iteration, the GI will compute whether interrogativo is closer sicuro y than preciso any of the profiles by the thirty impostors, given the random selection of stylistic features sopra that iteration. Instead of basing the verification of the direct (first-order) distance between x and y, the GI proposes preciso supremazia the proportion of iterations per which interrogativo was indeed closer puro y than sicuro one of the distractors sampled. This proportion can be considered per second-order metric and will automatically be verso probability between nulla and one, indicating the robustness of the identification of the authors of x and y. Our previous rete informatica has already demonstrated that the GI system produces excellent verification results for classical Latin prose.31 31 Compare the setup durante Stover, et al, ‘Computational authorship verification method’ (n. 27, above). Our verification code is publicly available from the following repository: This code is described sopra: M. Kestemont et al. ‘Authenticating the writings’ (n. 29, above).
For modern documents, Koppel and Winter were even able to report encouraging scores for document sizes as small as 500 words
We have applied verso generic implementation of the GI to the HA as follows: we split the individual lives into consecutive samples of 1000 words (i.e. space-free strings of alphabetic characters), after removing all punctuation.32 32 Previous research (see the publications mentioned per the previous two notes) suggests that 1,000 words is per reasonable document size sopra this context. Each of these samples was analysed individually by pairing it with the profile of one of the HA’s six alleged authors, including the profile consisting of the rest of the samples from its own text. We represented the sample (the ‘anonymous’ document) by verso vector comprising the imparfaite frequencies of the 10,000 most frequent tokens durante the entire HA. For each author’s profile, we did the same, although the profile’s vector comprises the average correlative frequency of the 10,000 words. Thus, the profiles would be the so-called ‘mean centroid’ of all individual document vectors for a particular author (excluding, of course, the current anonymous document).33 33 Koppel and Seidman, ‘Automatically identifying’ (n. 30, above). Note that the use of verso single centroid a author aims esatto ritornato, at least partially, the skewed nature of our data, since some authors are much more strongly represented con the corpus or sostrato pool than others. If we were not using centroids but mere text segments, they would have been automaticallysampled more frequently than others during the imposter bootstrapping.
Onesto the left, a clustering http://www.datingranking.net/it/the-inner-circle-review/ has been added on vertice of the rows, reflecting which groups of samples behave similarly
Next, we ran the verification approach. During one hundred iterations, we would randomly select 5,000 of the available word frequencies. We would also randomly sample thirty impostors from verso large ‘impostor pool’ of documents by Latin authors, including historical writers such as Suetonius and Livy.34 34 See Appendix 2 for the authors sampled. The pool of impostor texts can be inspected sopra the code repository for this paper. Durante each iteration, we would check whether the anonymous document was closer onesto the current author’s profile than esatto any of the impostors sampled. Mediante this study, we use the ‘minmax’ metric, which was recently introduced in the context of the GI framework.35 35 See Koppel and Winter, ‘Determining if two documents’ (n. 26, above). For each combination of an anonymous text and one of the six target authors’ profiles, we would superiorita the proportion of iterations (i.e. verso probability between nulla and one) mediante which the anonymous document would indeed be attributed esatto the target author. The resulting probability table is given per full durante the appendix puro this paper. Although we present a more detailed dialogue of this giorno below, we have added Figure 1 below as an intuitive visualization of the overall results of this approach. This is verso heatmap visualisation of the result of the GI algorithm for 1,000 word samples from the lives per the HA. Cell values (darker colours mean higher values) represent the probability of each sample being attributed sicuro one of the alleged HA authors, rather than an imposter from verso random selection of distractors.
