Databases Reference
In-Depth Information
T A B L E 6 . 8
Count array for second-order
contexts.
Context
Letter
Count
Cum
_
Count
th
i
1
1
Esc
1
2
Total_Count
2
hi
s
1
1
Esc
1
2
Total_Count
2
is
b
2
2
Esc
1
3
Total_Count
3
sb
i
1
1
t
1
2
Esc
1
3
Total_Count
3
bi
s
1
1
Esc
1
2
Total_Count
2
bt
h
1
1
Esc
1
2
Total_Count
2
T A B L E 6 . 9
Counts using Method A.
Context
Symbol
Count
prob
a
10
l
09
o
03
Esc
01
Total_Count
23
context (e.g.,
problem, proboscis
, etc.). In Method A, we assign a count of one to the escape
symbol, resulting in a total count of 23, which is one more than the number of times
prob
has
occurred. This situation is shown in Table
6.9
.
In this second method, known as Method B, we reduce the count of each of the symbols
a
l
, and
o
by one and give the escape symbol a count of three, resulting in the counts shown
in Table
6.10
.
The reasoning behind this approach is that if in a particular context more symbols can
occur, there is a greater likelihood that there is a symbol in this context that has not occurred
,
