Propp Revisited: Integration of Linguistic Markup into Structured Content Descriptors of Tales

Proppian fairy tale Markup Language (PftML)

Creating PftML was based on the insight that Propp's functions – organized in tables to categorize his observations – were analogous to metadata, and as such renderable by hierarchically arranged elements in eXtensible Markup Language (XML) documents. A tale consists of one or more moves and on a lower level of functions which are modeled as elements. Function elements themselves have XML attributes that allow for the efficient extraction of data from the text using XQuery from within a native XML database. The embedded structure of Proppian functions as represented by PftML markup is illustrated in Fig. 1 by an annotated excerpt from the English translation of the Russian fairy tale The Swan-Geese.

Note that Proppian functions are applied to relatively long, semantically coarse-grained textual chunks, i.e. sentences, but linguistic elements that convey a function actually encompass a shorter sequence of words; e.g. contrary to the markup in the example, both Command and Execution only pertain to linguistic units smaller than full sentences.

<Corpus>
<Folktale Title="The Swan-Geese" AT="480" NewAfanasievEditionNumber="113"
ProppConformity="Yes">
<Move>
<Preparation>
    <InitialSituation> Once upon a time a man and a woman lived with their daughter and small son. </InitialSituation>
    <CommandExecution>
        <Command subtype="Interdiction"> "Dearest daughter," said the mother, "we are going to work. Look after your brother! Don't go out of the yard, be a good girl, and we'll buy you a handkerchief." </Command>
        <Execution subtype="Violated"> The father and mother went off to work, and the daughter soon enough forgot what they had told her. She put her little brother on the grass under a window and ran into the yard, where she played and got completely carried away having fun.</Execution>
    </CommandExecution>
</Preparation>
<Villainy subtype="Kidnapping"> In swooped the swan-geese, snatched up the little boy, and flew away with him. </Villainy>
<ConsentToCounteraction> When the girl came back inside, her brother was missing! "Oh no!" she cried. She dashed here and there, but there was no sign of him. She called for him, cried, and wailed how angry mother and father would be, but her brother did not answer. </ConsentToCounteraction>
                

Integration of PftML with linguistic annotation

We propose to combine PftML with a stand-off, multi-layered linguistic markup scheme to ensure modularity and reusability of linguistic information associated with textual elements, supporting interoperability of fairy tales annotation in different languages and versions. As seen in Fig. 1, PftML is interleaving the Proppian annotation with the text. This in-line annotation strategy has some drawbacks: a text can hardly be annotated in fine-grained manner without losing readability, or with information originating from different sources e.g. indicating different views on narrative functions.

Stand-off annotation strategy, following the standardization initiatives for language resources conducted within ISO,⁴ stores annotation separately from the original text, linking these by referencing mechanisms. We adopt the ISO multi-layered annotation strategy, representing linguistic information on the following levels: segmentation of the text in tokens; morpho-syntactic properties of the tokens; phrasal constituencies; grammatical dependencies; semantic relations (e.g. temporal, co-referential), cf. (Ide and Romary, 2006).

We illustrate how the linguistic annotation layers can be combined with the PftML annotation in one stand-off annotation file, showing here only the morphosyntactic and constituency annotation, as they are applied to the first five tokens of the sub-sentence annotated with the 'Violated Execution' function in Fig. 1. In the morphosyntactic annotation, the value of the TokenID of the 12th word is pointing to the original data (e.g., daughter is the 12th token in the text).⁵

<wordForms>
    <W ID="w11" POS="ART" LEMMA="the" MORPH="Sg" tokenID="t11">the</W>
    <W ID="w12" POS="NN" LEMMA="daughter" MORPH="Sg" tokenID="t12">daughter</W>
    <W ID="w13" POS="ADV" LEMMA="soon" tokenID="t13">soon</W>
    <W ID="w14" POS="ADV" LEMMA="enough" tokenID="t14">enough</W>
    <W ID="w15" POS="VVFIN" LEMMA="forget" MORPH="Past" tokenID="t15">forgot</W>
    ... 
</wordForms>
                

In the constituency annotation level displayed below, words are grouped into syntactic constituents (e.g. the nominal phrase the daughter). The span of constituents is marked by the value of the features from and to, which are pointing to the previous morpho-syntactic annotation layer.

<phrases>
    <phrase id="p4" from="w11" to="w12" type="NP">the daughter</phrase>
    <phrase id="p5" from="w13" to="w14" type="ADVP">soon enough</phrase>
    <phrase id="p6" from="w15" to="w15" type="VG">forgot</phrase>
    <phrase id="p7" from="w16" to="w20" type="REL_COMP">what they had told her
    </phrase> ... 
</phrases>
                

PftML and (for example) word-level annotation can be combined in one stand-off XML element, where each specific PftML annotation receives a span of textual segments associated with it:

<Execution subtype="Violated" id="e1" inv_id="Command1" from="w11" to="w21"> </Execution>
                

The values w11 and w21 are used for defining a region of the text for which the Propp function holds; Command1 refers to the Interdiction function label used earlier in the text.⁶

Benefits for humanities research

The integrated annotation scheme enables narrative segmentation enhanced by additional information about the linguistic entities that constitute a given function. A folklore researcher might be interested in which natural language expressions correspond to which narrative function: in the <Execution subtype="Violated"> example, forgot can be an indicator of this function. In fact, it is also relevant to signal that forgot is a verb, and to reduce the strings forgets, forgot, forgotten to one lemma (i.e. base form), so that all morphological forms are retrieved when any of these variants is queried.

Navigating through the different types of IDs included in the multilayered annotation, a researcher can obtain statistics over linguistic properties of fairy tales. For example, the grammatical subject of a function can be extracted, e.g. to see which characters participate in commands and their violation. Note that if – according to the current scheme – the narrative function boundaries are imprecise, the <Execution subtype="Violated"> function in our example sentence would incorrectly contain two grammatical – and three semantic – subjects (father and mother, and daughter).

Linguistic information will enable detecting functions that refer to each other, as syntax and semantics of sentence pairs in such relations mirror – at least partly – each other, e.g. Don't go out of the yard and ran onto the street. Detecting cross-reference in turn contributes to identifying a function's core elements, which is a crucial step in understanding the linguistic vehicles by which motifs operate and the degree of variation and optionality they allow.

Concluding remarks

Since the content descriptors in PftML might pertain to textual material on the supra- or subsentential level, there is a need to investigate the mechanisms underlying the assignment of a function to a span of words. We propose to tackle this issue based on linguistic analysis, hypothesizing that boundaries of certain linguistic objects overlap with boundaries of Proppian functions. A direct consequence of more precise segmentation of functions is that linguistic characterization, retrieval, and further computational processing of texts from the folktale genre will improve, and facilitate detecting higher-level, domain-specific cognitive phenomena. It would also become feasible to detect from corpus evidence if there exist additional functions beyond Propp's scheme.

Integration along the above lines with ontological resources of fairy tales is described in a separate study by us (Lendvai et al., 2010). We expect from our strategy – applied to tales in different versions in different languages – to lead to the generation of a multilingual ontology of folktale content descriptors, which would be extending the efforts of the MONNET project,⁷ originally focussing on financial and governmental issues. In future work we plan to address embedding our annotation work into the TEI framework,⁸ and extend the ISO strategy on using well-defined data categories for linguistic annotation labels⁹ to those of functions corresponding to PftML labels, to facilitate porting our approach to other literary genres.

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