Download full issue (PDF 2.1MB) - Council of European ...

Information Technologies for Visually Impaired People
Figure 5: Transcription of Formula (1) in several Braille Mathematical Notations.
2.2 Main Strategies
Let us consider the transcription of formula (1) in Figure
2 in several Braille Mathematical notations (see Figure
5).
The number of available Braille symbols is quite reduced:
6 dots which can be combined in a maximum of 64
different patterns. Therefore it is necessary to use multiple
Braille characters to code most Mathematical symbols. The
various Braille notations implement different strategies for
dealing with that problem. In Italian, the digits and the letters
are always written using 2 symbols, the first indicating
whether it is a digit or a letter and in the latter case which
kind of letter (in the formula (8) for instance, "1" is
the first symbol standing for digit, while "x" is
where the first symbol means it is a Roman letter). British
uses the same rule, but users will omit the prefix in the
case of a symbol which cannot be a number (numbers are
represented by the 10 first letters), like ‘x’ here
( ).
In Marburg the prefix for Latin letters is used only the
first time, like a switch, indicating that any other instance
of ‘x’ in the formula is of the same type (lower case Roman
for instance here). Digits are always preceded by the
symbol. Finally in French the most frequent case is always
assumed (lower case Roman), and there is a prefix
before each other (upper case, Greek, etc.). There is also a
special way to represent digits adding the dot ‘6’ to the corresponding
letter traditionally used: instead of
the single symbol
is used (this is called the 'Antoine' notation for digits).
This make simple formulas shorter. Nemeth differentiates
also the digits from letters by using different Braille patterns.
Here the numbers that are written in the lower part of
the Braille cell: 1 is represented by
Let us now consider the fraction itself. Block markers
identify the numerator and the denominator. In French,
Marburg and British notations the blocks are always the
same; making it necessary to reach the fraction symbol to
determine that this is in fact a fraction. The fraction structure
itself uses 5 symbols, 2 pairs of block markers and a
fraction mark (for example in French:
... ... ).
On the contrary in Italian the numerator and the denominator
markers are not the same; there is no fraction symbol
and the fraction structure uses only 4 symbols
34 UPGRADE Vol. VIII, No. 2, April 2007 © Novática
.
(6)
(7)
(8)
(9)
(10)
(11)