From: pat hayes (phayes@ai.uwf.edu)
Date: 06/27/02
Richard, on going through your document with a fine comb, Ive a few more niggling questions/suggestions, which Ill summarize here in case you (or anyone) wants to jump on them. It may not be practical for every answer to specify the answer KB used to generate it. For many servers this information may be proprietary, in any case. So I don't think we should require this. However, that raises a new question: should we allow a *query* to say that it will only accept answers with an answer KB specified? I think that would be good. One general way to handle this would be have the query contain a 'KB specification' which could be either a list of urirefs (KB names) or one of the three kinds of variable. A must-bind variable means, I must know the answer KB. A no-bind means I don't care. Bindings to these variables are allowed to be arbitrary lists of urirefs, to allow for the case where the server uses a lot of KBs in its answer. Then Yahoo (say) can just refuse to accept queries with a must-bind KB spec, for example. Another, related, question. Suppose the query specifies the answer KB to be used, but the server simply doesn't know the KB uriref? It could just hand back 'unknown', but it would be more informative to allow a new kind of token, maybe 'unknown-KB'. In general, we should write the spec so that things like the set of tokens can be extended in future, in any case, right? A question about 'none'. Do we want this to mean that there are no other answers entailed by the KB, or that there are no other answers *which fit the specifications of the query* that are entailed, or that there are no other answers *of the kind that this server knows how to reason about* that are entailed....? Or maybe something else? I guess I am suspicious about it being possible for most servers to be absolutely certain that there are no other entailed answers *at all*. At any rate, we need to be painfully exact about what we do mean, and Im not sure that just saying 'no further answers are entailed' is exactly what we intend here (?). Since we don't say what a justification is, and since there isnt (yet) any defined notion of 'proof' in DAML, why not just omit this, and just say that an answer might contain other stuff to be defined in future, and a query might contain other stuff which is relevant to said other stuff in the answer (???) Should we allow a query to specify any (lower or upper) bounds of the number of answers it wants per answer bundle? An upper bound seems like it might be useful. Finally, do we want to allow the case where a query premis is specified, but no other KB is allowed to be used? If so, how does the query specify that? Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
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