1 | package de.ugoe.cs.eventbench.models;
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2 |
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3 | import java.io.Serializable;
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4 | import java.util.Collection;
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5 | import java.util.List;
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6 |
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7 | import de.ugoe.cs.eventbench.data.Event;
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8 |
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9 | /**
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10 | * <p>
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11 | * This interface defines the functionalities provided by stochastic processes.
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12 | * </p>
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13 | *
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14 | * @author Steffen Herbold
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15 | * @version 1.0
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16 | */
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17 | public interface IStochasticProcess extends Serializable {
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18 |
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19 | /**
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20 | * <p>
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21 | * Returns the probability, that the next event is {@code symbol} given the
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22 | * last events are {@code context}. The last element of {@code context} is
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23 | * the most recent in the history, the first element is the oldest.
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24 | * </p>
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25 | *
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26 | * @param context
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27 | * recently observed symbols
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28 | * @param symbol
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29 | * event for which the probability is calculated
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30 | * @return probabilty the {@code symbol} is the next event, given the last
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31 | * events {@code context}
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32 | */
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33 | double getProbability(List<? extends Event<?>> context, Event<?> symbol);
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34 |
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35 | /**
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36 | * <p>
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37 | * Generates a random sequence of events. The sequence starts with
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38 | * {@link Event#STARTEVENT} and finishes with {@link Event#ENDEVENT}.
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39 | * </p>
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40 | *
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41 | * @return randomly generated sequence
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42 | */
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43 | public List<? extends Event<?>> randomSequence();
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44 |
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45 | /**
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46 | * <p>
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47 | * Generates all sequences of a given length are possible, i.e., have a
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48 | * positive probability.<br>
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49 | * All states are used as possible starting states.
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50 | * </p>
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51 | *
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52 | * @param length
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53 | * length of the generated sequences
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54 | * @return generated sequences
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55 | * @see #generateSequences(int, boolean)
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56 | */
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57 | public Collection<List<? extends Event<?>>> generateSequences(int length);
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58 |
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59 | /**
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60 | * <p>
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61 | * Generates all sequences of given length that can are possible, i.e., have
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62 | * positive probability.<br>
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63 | * If {@code fromStart==true}, all generated sequences start in
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64 | * {@link Event#STARTEVENT}. Otherwise this method is the same as
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65 | * {@link #generateSequences(int)}.
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66 | * </p>
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67 | *
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68 | * @param length
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69 | * length of the generated sequences
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70 | * @param fromStart
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71 | * if true, all generated sequences start with
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72 | * {@link Event#STARTEVENT}
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73 | * @return generated sequences
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74 | */
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75 | public Collection<List<? extends Event<?>>> generateSequences(int length,
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76 | boolean fromStart);
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77 |
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78 | /**
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79 | * <p>
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80 | * Generates all sequences starting with {@link Event#STARTEVENT} and
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81 | * finishing with {@link Event#ENDEVENT} of a given length. It is possible
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82 | * that no such sequence exists with the defined length and the returned set
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83 | * is empty. If {@code length} is less than 2 the returned set is always
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84 | * empty.
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85 | * </p>
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86 | *
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87 | * @param length
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88 | * @return generated sequences
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89 | */
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90 | public Collection<List<? extends Event<?>>> generateValidSequences(int length);
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91 |
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92 | /**
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93 | * <p>
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94 | * Returns the number of states known by the stochastic process, i.e., the
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95 | * size of its alphabet.
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96 | * </p>
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97 | *
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98 | * @return number of states
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99 | */
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100 | public int getNumStates();
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101 |
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102 | /**
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103 | * <p>
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104 | * Returns a string representation of all known states.
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105 | * </p>
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106 | *
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107 | * @return string representation for all known states
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108 | */
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109 | public String[] getStateStrings();
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110 |
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111 | /**
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112 | * <p>
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113 | * Returns all states known by the stochastic process, i.e., its
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114 | * {@link Event}s.
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115 | * </p>
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116 | *
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117 | * @return events known by the process
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118 | */
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119 | public Collection<? extends Event<?>> getEvents();
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120 |
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121 | } |
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