Finn Årup Nielsen,
Thank you. The techniques could be of use for a number of projects; I chose http://machine.wikipedia.org for brainstorming purposes. I chose the example prefix “mw” for “machine Wikipedia” but we could use another prefix. Similarly with the placeholders for P1, P2.
My initial thoughts with respect to optional arguments and variadic predicates are that URL-addressable syntaxes support variadic predicates if a system is such that predicates can be defined with indefinite arity with respect to their T0, T1, T2 and/or A0, A1, A2 parameters.
With respect to what is returned, my initial thinking is that the output varies based on HTTP request headers, in particular Accept and Accept-Language . For the Accept values of “text/html” or “application/xhtml+xml”, the content returned could be human-readable wiki content. Other interesting formats to consider include “application/rdf+xml”. For predicates without arguments, e.g. for URLs resembling http://machine.wikipedia.org/P1 and http://machine.wikipedia.org/P2?T0=t0&T1=t1&T2=t2 , the definitions of predicates could be accessed or outputted.
With respect to error messages, in addition to the HTTP return codes of 4xx and 5xx, some requested formats may be able to encode error-related data.
Best regards,
Adam Sobieski
________________________________ From: Wiki-research-l wiki-research-l-bounces@lists.wikimedia.org on behalf of fn@imm.dtu.dk fn@imm.dtu.dk Sent: Wednesday, October 17, 2018 7:40:52 AM To: wiki-research-l@lists.wikimedia.org Subject: Re: [Wiki-research-l] URL-addressable Predicate Calculus
Interesting.
Why would you have the prefix "https://machine.wikipedia.org/". This could be useful for many projects particular Wikidata, - not just wikipedia. Would "https://wikimachine.org/" or something be better?
"mw" is used as prefix for https://www.mediawiki.org and mw2sparql https://www.mediawiki.org/wiki/MW2SPARQL
"mw:P2<t0, t1, t2>" does not seem to be supported by SPARQL and < and > are not allowed in IRI_REF. Ordinary parentheses seems to be allowed. The rule is '<' ([^<>"{}|^`]-[#x00-#x20])* '>'
"mw:P1(arg0, arg1, arg2)" and "mw:P2<t0, t1, t2>" Why are there two kinds of input? Wouldn't one suffice.
"mw:P1" Why are the identifiers prefixed with P? That collides with the Wikidata properties.
"mw:P1(arg0, arg1, arg2)" This form does not allow for optional arguments.
There is also the question of what should be returned. There should be room for error messaging.
One idea I have not followed through is to make an empty SPARQL endpoint that would just provide SPARQL functions (extension functions). This way the function could possibly be used in a federated query.
best regards Finn Årup Nielsen
On 10/17/18 11:32 AM, Adam Sobieski wrote:
I would like to share, for discussion, some knowledge representation ideas with respect to a URL-addressable predicate calculus.
In the following examples, we can use the prefix “mw” for “https://machine.wikipedia.org/%E2%80%9D as per xmlns:mw="https://machine.wikipedia.org/" .
mw:P1 → https://machine.wikipedia.org/P1
mw:P1(arg0, arg1, arg2) → https://machine.wikipedia.org/P1?A0=arg0&A1=arg1&A2=arg2
mw:P2 → https://machine.wikipedia.org/P2
mw:P2<t0, t1, t2> → https://machine.wikipedia.org/P2?T0=t0&T1=t1&T2=t2
mw:P2<t0, t1, t2>(arg0, arg1, arg2) → https://machine.wikipedia.org/P2?T0=t0&T1=t1&T2=t2&A0=arg0&A...
Some points:
There is a mapping between each predicate calculus expression and a URL.
Navigating to mapped-to URLs results in processing on servers, e.g. PHP scripts, which generates outputs.
The outputs vary per the content types requested via HTTP request headers.
The outputs may also vary per the languages requested via HTTP request headers.
Navigating to https://machine.wikipedia.org/P1 generates a definition for a predicate.
Navigating to https://machine.wikipedia.org/P2?T0=t0&T1=t1&T2=t2 generates a definition for a predicate after assigning values to the parameters T0, T1, T2. That is, a definition of a predicate is generated by a script, e.g. a PHP script, which may vary its output based on the values for T0, T1, T2.
The possible values for T0, T1, T2, A0, A1, A2 may be drawn from the same set. T0, T1, T2 need not be constrained to be types from a type system.
The values for T0, T1, T2, A0, A1, A2, that is t0, t1, t2, arg0, arg1, arg2, could also each resolve to URLs.
Best regards, Adam Sobieski http://www.phoster.com/contents/
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