Poetry Generation with PoeTryMe - Computational Creativity Research: Towards Creative Machines - page 236

for the development of different poetry generation systems. Several of its components
can be changed: the base semantics, represented as relation instances; the sentence
templates, included in the generation grammars; the generation strategies, that select
and organise the lines to include in the poem; and, of course, the poem configuration,
which sets the target number of stanzas, lines and their size. The combination of all
these components enables the generation of a diverse set of poems, thus contributing
to a positive perception of creativity.
We start this chapter by referring some work on the automatic generation of poetry,
including two groupings for this task. Then, we present an overview on the architec-
ture of PoeTryMe, followed by a detailed description of our approach to the automatic
generation of poetry, in Portuguese. Each decision of our approach is described step-
by-step, from an enumeration of the resources used and the process for acquiring
line templates, to the implemented generation strategies and the contextualization
of the poems. Before concluding, we compare the implemented strategies regarding
several features, including the diversity of the poems they produce, the time they take
to produce them, and the score of the produced poems, which considers how they
match a target metre as well as the rhymes they use. Together with the comparison
numbers, the results of each strategy are illustrated with a generated poem, which
gives an idea of what we can do with PoeTryMe.
12.2 Automatic Generation of Poetry
The automatic generation of poetry is a complex task, as it involves several levels of
language (e.g. phonetics, lexical choice, syntax and semantics) and usually demands
a considerable amount of input knowledge. What makes this task more interesting
is that some of those levels do not have to be strictly addressed.
On the one hand, writing poetic text does not have to be an extremely precise
task [ 10 ], as several rules, typically present in the production of natural language, need
to (or should) be broken [ 24 ]. On the other hand, poetry involves a high occurrence of
interdependent linguistic phenomena where rhythm, metre, rhyme and other features
like alliteration and figurative language play an important role. For instance, it is ok
to have a not very well-defined message, in a trade-off for a pleasant sound given by
a highly regular metre.
In this section, we present two groupings of poetry generation systems, proposed in
the literature. One of themconsiders the applied techniques and another the properties
of the generated text.
12.2.1 Poetry Generation Techniques
Regarding the followed approaches and applied techniques, Gervás [ 12 ] groups
poetry generation systems into five categories: