Information Technology Reference
In-Depth Information
Messages for Selection
In information theory, the messages for selection are the messages exist-
ing in the source from which the information source selects to compose a
message. Classically, the messages for selection are conceived at the level
of granularity of the individual character or letter of the alphabet of char-
acters for selection (Shannon 1948/1993). Restricting the lowest level
of granularity at which the messages for selection are conceived to the
individual character avoids the necessity of direct attention to such fea-
tures as intercharacter or mosaic differentiation and redundancy but still
acknowledges the existence and function of these features (Cherry 1978).
The level of granularity chosen is consistent with the understanding of the
message adopted—orthographically acceptable written sequences from
the English language lexicon, compounded of letters and other characters
from the messages for selection.
Messages for selection can be conceived as held in a reservoir or scat-
tered across a surface, in contrast to the surface organization often con-
sidered essential to representing the paradigm. Within information theory,
the lack of organization implied in a reservoir or scattering across a sur-
face is analogous to the formalized concept of entropy. Real historical ana-
logues to a store, or reservoir, of messages for selection can be considered
at increasing levels of organization within the messages for selection and
not yet concatenated into a linear message, although possibly anticipat-
ing the relative distribution of the messages for selection in the message.
Clarity in exposition can be obtained by restriction to a single alphabet
(in this instance, the lower case Roman alphabet), although the concept of
an alphabet could extend to other sets of characters. For instance, a rela-
tively unorganized reservoir could be conceived as a container that holds
equal numbers of individual letters. Combinations blindly chosen or ran-
domly generated from the reservoir might be difficult to form into cohe-
sive units or words in a given language, even on a purely pattern-based
and computationally realizable basis, and a residue of unusable letters
might remain after the formation of units (for instance,
qqq
,
xxx
,
zzz
). At
a further level of organization, the distribution of letters in the reservoir
could correspond to the relative distribution of letters in messages of the
intended language; blind selections would then be more amenable to con-
catenation into lexically cohesive units or words, and there need only be
a limited, possibly nil, residue of unusable characters. (
Scrabble
®
players
