A reasoner using Webized ISO Prolog:
| TERM | Examples |
|---|---|
| IRI | 'urn:example:abc' |
| BLANKNODE | '_:bn_1' |
| VARIABLE | X _abc |
| LITERAL | "abc" true 1.52 1e-18 pi |
| LIST | [TERM,...] [TERM,...|LIST] |
| COMPOUND | IRI(TERM,...) |
| TRIPLE | IRI(TERM,TERM) GRAPH => GRAPH |
| GRAPH | TRIPLE,... |
| CLAUSE | Examples |
|---|---|
| ASSERTION | TRIPLE. true => GRAPH. |
| FORWARD_RULE | GRAPH,PROLOG (*) => GRAPH. |
| QUERY | GRAPH => true. |
| ANSWER | GRAPH => true. |
| INFERENCE_FUSE | GRAPH => false. |
| BACKWARD_RULE | TRIPLE <= GRAPH,PROLOG. |
(*) Use stable(n) to fail if the deductive closure at level n is not yet stable.
It performs forward chaining for a FORWARD_RULE and backward chaining for a BACKWARD_RULE.
Queries are posed and answered as GRAPH => true. so the answers are also queries be it with
some parts substituted and eventually containing more variables than in the original query.
This forms a dialogue leading to necessary and sufficient answers, supported by proof steps, so that action can take place.
Proofs are made of:
proof((prem => conc),prem_inst,conc_inst).
Install Trealla Prolog and run
cd etc
./test
- Personal notes by Tim Berners-Lee: Design Issues
- Book of Markus Triska: The Power of Prolog