
| Action Choices       |               |              |               |             |             |     |    |    |    |             |
|----------------------|---------------|--------------|---------------|-------------|-------------|-----|----|----|----|-------------|
| Operations Variables |               |              |               |             |             |     |    |    |    |             |
| U                    | S             | H            |               |             |             |     |    |    |    |             |
| I                    | R             | P            | G             | M           | W           | S C | C  | T  | L  | AskUserName |
| SI Top  MI Top       |               |              |               |             |             |     |    |    |    |             |
| SI Top Help          |               |              |               |             |             |     |    |    |    |             |
| S                    |               |              |               |             |             |     |    |    |    |             |
| si                   | SI Top Reject |              |               |             |             |     |    |    |    |             |
| SI                   | s             | S S S S CP   |               |             |             |     |    |    |    |             |
| AskWS                |               |              |               |             |             |     |    |    |    |             |
| SI                   | R             |              |               |             |             |     |    |    |    |             |
| SI                   | R             | AskWS Reject |               |             |             |     |    |    |    |             |
| SI                   | R             | Snd          | AskSC         |             |             |     |    |    |    |             |
| SI                   | R             | Sn d         | AskSC TimeOut |             |             |     |    |    |    |             |
| SI                   | RF RSO RCP    |              |               |             |             |     |    |    |    |             |
| R                    | N             | Snd          |               |             |             |     |    |    |    |             |
| SI                   | RCP           | R            | Snd           | ReadMessage |             |     |    |    |    |             |
| SI                   | RCF           | SI Top       |               |             |             |     |    |    |    |             |
| MI                   | MI Top Help   |              |               |             |             |     |    |    |    |             |
| MI                   | MI Top Reject |              |               |             |             |     |    |    |    |             |
| MI                   | S S S S C P   |              |               |             |             |     |    |    |    |             |
| MI                   | RF RSO RCP    |              |               |             |             |     |    |    |    |             |
| SS                   | R             | N            | Snd           |             |             |     |    |    |    |             |
| MI                   | S             | R            | R             | Snd         | ReadMessage |     |    |    |    |             |

A portion of ELVIS s operations state machine using the full operations vector to control ELVIS s behavior about what the users current goal is The WhichSelection W variable tracks whether the system knows what type of selection criteria the user would like to use to read her The KnowSelectionCriteria  SC  variable tracks whether the system believes messages it understood either a sender name or a subject name to use to select messages The NumMatches  M  variable keeps track of how many messages match the user s selection criteria  The Confidence  C  variable is a threshholded variable indicating whether the speech recognizer s confidence that it understood what the user said was above a pre set threshhold  The Timeout  T  variable represents the system s belief that the user didn t sy anything in the allotted time The Help H variable represents the system s belief that the user said Help and leads to the system providing context specific help messages  The Cancel  L  variable represents the system s belief that the user said Cancel  which leads to the system resetting the state to the state before the last user utterance was processed possible states used to control the operation of the system  although Thus there are not all of the states occur 3 In order for the reader to achieve a better understanding of the range of E LVIS s capa bilities and the way the operations vector is used Figure shows a portion of ELVIS s state machine that can generate the sample system and mixed initiative dialogue interactions in Figures   and Each of these figures provides the state representation and the strat egy choices made in each state of the sample dialogues  For example  row two of Figure shows that after the system acquires the user s name  KnowUserName  U
with high confidence   Confidence   C
that it can explore the system initiative  SI Top  or