>724401 Verzweigungen

Railroad Diagrams Branchings

Production

              .-.
|-|--->.---->( X )--->.--->|-|
       |      '-'     ^
       |      .-.     |
       '---->( Y )----'
              '-'

When passing a branching, any branch can be chosen (as long as there is no movement against an arrow direction).

We show two possible results of the above production.

Result

The text set described by the diagram

X, Y

Each time a non-terminal is passed, a different text can be chosen.

Production

B
              .-.
|-|--->.---->( X )--->.--->|-|
       |      '-'     ^
       |      .-.     |
       '---->( Y )----'
              '-'
C
       .---.    .---.
|-|--->| B |--->| B |--->|-|
       '---'    '---'

A possible result of the production C

XY

The text set described by production C

XX, XY, YX, YY

Railroad diagrams are used to describe text sets in a structured manner. (A text set is a collection of different texts.)

Practice Questions

? Practice Question

Production

             .-.
|-|--->.--->( A )--->.--->|-|
       |     '-'     ^
       |     .-.     |
       '--->( B )----'
       |     '-'     ^
       |     .-.     |
       '--->( C )----'
             '-'

Give exactly one possible result of the above production rule.

? Practice Question 1

Production

             .-.
|-|--->.--->( A )--->.--->|-|
       ^     '-'     |
       |     .-.     |
       '----( B )<---'
             '-'

Give exactly one possible result of the above production rule that includes at least two characters.

NB: There now is an arrow pointing to the left !

? Practice Question 2

Production

            .-----------.
|-|--->.--->| character |--->.--->|-|
       ^    '-----------'    |
       |                     |
       '---------------------'

Give exactly one possible result of the above production rule that includes at least two characters.

? Practice Question 3

Production

        .-.                                .-. 
|-|--->( " )--->.------------------->.--->( " )--->|-|
        '-'     ^                    |     '-'
                |   .-----------.    |
                '---| character |<---'
                    '-----------'

Give exactly one possible result of the above production rule that contains as few characters as possible.

? Practice Question 4

Give exactly one possible result of the above production rule (from practice question 3) that comprises four characters.