Information Technology Reference
In-Depth Information
Fig. 2.58
Multiplicity-length distribution of repeats in Escherichia coli
and styles, character dimensions, and structural information (paragraphs, sections,
titles, footnotes, ...). When such a rich structure of text is represented in a pure
textual format, for example in terms of ascii code, then the whole information is
encoded in suitable manners by means of a complex process of representation. For
the sake of clarifying the idea, we can refer to modern languages for text representa-
tion such as Tex, Latex, or XML (see [41, 42] for examples of XML representation
of linguistic structures). However, the encoding process is very strict. If we delete
from a Latex file only a few characters, then it becomes useless and its compilation
providing the text it represents cannot be successfully realized. Genomes need to
realize a complex informational structure, but they are pure linear structures which
require a high level of
flexibility
. DNA is a sort of associative memory, no addresses
are available, as in electronic memories, therefore hapaxes can play an essential role
in localizing and coordinating pieces containing specific meanings. In this perspec-
tive, the semantics of words do not depend on their absolute positions, but on their
relative positions in a system of anchors or markers for correctly determining some
elements within the genomic superstring where they occur.
Tables 2.19, 2.20, 2.21, 2.22, and 2.23 are examples of complex texts, such as a
web page or a mathematical formula. They are represented at different levels. The
information, at any level, is the same, but the “comprehension” at different levels
is very different. In the first case the meaning underlying in Tables 2.19 and 2.20
is a famous web page, which everybody uses frequently as Web search engine. Its
meaning is very clear and any component of the page can be easily recognized with
its specific function. However, it is hard to recognize this meaning in the representa-
tions given in the mentioned tables. The second example is an elementary algebraic
formula (for solving quadratic equations). Its meaning is clear to anybody having
basic mathematical skills. However, also in this case, it is difficult to recognize its
meaning from Tables 2.22 and 2.23. These examples intend to stress the importance
of discovering the structure of a text from its basic linear representation where the
