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Communication between Embodied AVAs

 

In the discussion so far presented, the distinguishing feature of embodied AVAs is characterized by tex2html_wrap_inline1354 . Here we will show that carrying a physical body has further implications.

Let tex2html_wrap_inline1344 denote an embodied AVA (Fig. 6). Then, first of all, carrying a physical body implies that (some part of) tex2html_wrap_inline1348 can be observed from other AVAs;

   figure210
Figure 6: Model of an embodied AVA.

Thus, tex2html_wrap_inline1304 in equation (1) may include tex2html_wrap_inline1348 . To estimate tex2html_wrap_inline1348 from tex2html_wrap_inline1304 , we define the following new function:

  equation223

Note that in order for tex2html_wrap_inline1394 to function meaningfully, tex2html_wrap_inline1298 must first identify the existence of tex2html_wrap_inline1344 and then should have the knowledge about how tex2html_wrap_inline1348 is reflected onto its physical body and/or the world.

While how to obtain such object identification and knowledge is an important problem to be studied, here we assume they are given; tex2html_wrap_inline1298 and tex2html_wrap_inline1344 share the knowledge about the physical reflection of tex2html_wrap_inline1348 . Then, tex2html_wrap_inline1344 can inform tex2html_wrap_inline1298 of its state tex2html_wrap_inline1348 without sending a message:

  1. First tex2html_wrap_inline1344 embeds tex2html_wrap_inline1348 into tex2html_wrap_inline1300 using tex2html_wrap_inline1420 and/or tex2html_wrap_inline1422 .
  2. tex2html_wrap_inline1298 obtains tex2html_wrap_inline1304 by tex2html_wrap_inline1310 and then extracts tex2html_wrap_inline1348 by applying
    tex2html_wrap_inline1394 .
  3. Finally, the extracted tex2html_wrap_inline1348 is used by tex2html_wrap_inline1436 to change tex2html_wrap_inline1324 , since tex2html_wrap_inline1304 in equation (9) contains tex2html_wrap_inline1348 .
This series of processes simulate tex2html_wrap_inline1444 followed by tex2html_wrap_inline1350 .

When tex2html_wrap_inline1298 is also an embodied AVA, the mutual exchange of tex2html_wrap_inline1324 and tex2html_wrap_inline1348 can be realized without exchanging messages. That is, the communication without message exchange can be realized between embodied AVAs. This property is the most crucial feature discriminating embodied from vacuous AVAs. Note that all software agents are vacuous and lack this property.

As mentioned before, to realize the communication without message exchange, the object identification should be established and the knowledge about how the physical state reflects the internal state should be shared between AVAs. These two factors can be considered as defining the essence of Languages. In case of talking with hands, for example, the object identification implies the recognition of a ``speaker'' and the shared knowledge the specific chirology used. We believe the language is an abstract information structure used for communication and can be represented by various different media: physical bodies, sounds, visual patterns, and symbolic messages. From an information processing point of view, the complexity and efficiency of communication may depend on the media; symbolic messages seem to be more efficient and can represent more complex information than physical body actions. If so, we should use the message exchange for communication even if all AVAs are embodied.

   figure255
Figure 7: Multi-channel communication between embodied AVAs.

When an embodied AVA has the message exchange capability, it has two different ways of communication: action-perception and message exchange (Fig. 7). Two pieces of information carried by an action and a message should be consistent since a sender AVA is a rational agent. This means that the former constrains the latter and vice versa. In other words, tex2html_wrap_inline1346 constrains and simulates tex2html_wrap_inline1312 and/or tex2html_wrap_inline1354 . From equation (5), for example, tex2html_wrap_inline1346 can encode into tex2html_wrap_inline1340 such parts of tex2html_wrap_inline1324 that represent tex2html_wrap_inline1298 's physical body state and/or its ``future'' action plan. Then, using tex2html_wrap_inline1468 defined in equation (6), the receiver tex2html_wrap_inline1344 changes its internal state to form ``quasi-percept'' of and/or ``expectation'' about tex2html_wrap_inline1298 's body state. The action by the sender tex2html_wrap_inline1298 , on the other hand, is constrained so that its physical body action may be consistent with the quasi-percept of and/or the expectation formed in tex2html_wrap_inline1344 . This means that in some cases, the message exchange plays the same role as the action-perception. This phenomenon has been know as speech act in linguistics[3].

In summary, the communication between embodied AVAs is best characterized by multi-channel communication links formed by versatile combinations of perception, action and message exchange processes (Fig. 7).


next up previous
Next: Discussions Up: Integrating PerceptionAction, and Previous: Communication between Vacuous AVAs