Information Technology Reference
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2.2
From Automata Descriptions to Automata
Similarly to the text-to-MSC translation, it is possible to translate text pieces describing
automata to automata themselves, as presented in [6]. The difference lies in the relation
between sentences that we have to model. This can be illustrated on the specification
excerpt in Table 1 (from [7]). The header and the first sentence of this excerpt set the
context (“normal mode”), and further sentences refer to this context. Thus, instead of a
message stack, we have to model the context setting and the usage of the set context.
Ta b l e 1 . The Steam Boiler, specification excerpt (copied from [7])
Normal mode
1. The normal mode is the standard operating mode in which the program tries to maintain
the water level in the steam-boiler between N1 and N2 with all physical units operating
correctly.
2. As soon as the water level is below N1 or above N2 the level can be adjusted by the
program by switching the pumps on or off.
3. The corresponding decision is taken on the basis of the information which has been
received from the physical units.
We model the context by assigning every (sub)sentence to one of the four categories:
“state transition”, “transition condition”, “context setting”, or “irrelevant”. The assign-
ment of sentence segments to categories takes place in the following steps: (1) splitting
of every sentence to segments, (2) assignment of segments to categories on the basis
of grammatical information only, and (3) re-assignment of segments to categories, by
using context information. Each of these steps is described below.
Sentence splitting: Punctuation symbols, the words “if” and “when” as well as the
conjunctions “and” and “or” are used as splitting marks, unless they directly follow an
adjective or a number. 1 A splitting example is shown in Table 2.
Ta b l e 2 . Splitting example
Original sentence
As soon as this signal has been received, the program enters either the mode normal if all
the physical units operate correctly or the mode degraded if any physical unit is defective
Splitting
1. As soon as this signal has been received
2. the program enters either the mode normal
3. all the physical units operate correctly
4. the mode degraded
5. any physical unit is defective
1
These heuristics prevent splitting of, e.g., “if the water level lies between N1 and N2, ...”.
 
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