SCIFF Developer's Manual

SCIFF debugger

During the trace (not the CHR trace), it is possible to visualise the quantification of the variables.

If SICStus is trying to invoke a goal, e.g.:

Call: module:predicate(A,B,C)

to visualise the quantification of the variables, act as follows.

• hit 'b' (break level)
• invoke the goal: print_quant(module).
  where 'module' is the name of the module of the predicate SICStus was going to Call.
  If the module is not present, simply call print_quant.
• exit from break level (^D in Linux, ^Z in Windows)

graphviz

Represents the sciff derivation tree in form of a graph, using the graphviz software.

The file should be opened with init_graph(FileName,Stream), and, after the execution of the proof, it should be closed with close_graph. The produced file can be opened with DOT and converted in PostScript or other formats.

Default value is off.

ics

From a low-level point of view, the integrity constraints are represented as CHR constraints. If you want to add an IC which is not allowed by the parser, you have to:

• state the quantification of all the variables that occur in the IC
• invoke the IC.

in order to set the quantification of a variable X in an integrity constraint, invoke the goal forall(X) or exists(X).

The ic is represented as psic(Body,Head), where

• Body is a list [H,NotH,E,NotE,En,NotEn,Abd,A], where H is a list of atoms h(Event,T), NotH is a list of noth(Event,T), E is a list of e(Event,T), NotE is a list of note(Event,T), En is a list of en(Event,T), NotEn is a list of noten(Event,T), Abd is a list of abd(Event,T), and A is a list of atoms.
• Head is a list of lists. The list of lists represents a disjunction of conjunctions

remember that all the atoms have a Prolog syntax, i.e., they are lowercase (e.g., happened events are represented as h(Event,T))

For example, if you want to add the following IC:

where for some reason you want Tq quantified existentially and Tr universally, you can invoke the goal:

forall(Tp), forall(Tr), exists(Tq), exists(Ts), psic([[h(p,Tp)],[],[],[],[],[],[],[]],[[en(q,Tq),e(r,Tr)],[e(s,Ts)]]).

Example:

?- forall(Tp), forall(Tr), exists(Tq), exists(Ts), psic([[h(p,Tp)],[],[],[],[],[],[],[]],[[en(q,Tq),e(r,Tr)],[e(s,Ts)]]), h(p,1).
pending(en(q,_A)),
pending(e(r,_B)),
psic([[h(p,Tp)],[],[],[],[],[],[],[]],[[en(q,Tq),e(r,Tr)],[e(s,Ts)]]),
h(p,1),
en(q,_A),
e(r,_B) ? ;
pending(e(s,_A)),
psic([[h(p,Tp)],[],[],[],[],[],[],[]],[[en(q,Tq),e(r,Tr)],[e(s,Ts)]]),
h(p,1),
e(s,_A) ? ;
no

RuleML

SCIFF can use as ICs files also files represented in RuleML 0.9.

Moreover, SCIFF can convert ICs from the internal representation into RuleML, using the predicate save_ics_ruleml(FileName) in the module ruleml_parser.

For example, after opening a project (e.g., project(auction)), use the command

to save the ICs in the project to a file ic.ruleml in RuleML format.

download_ics

The predicate download_ics/1 lets you download an ICS file from the web. The only parameter is the URL of the ICS file, given as string (i.e., with double quotes "") The ICS file can be either in the ICS syntax, or in RuleML. The ICS are then imposed (i.e., they are invoked).

help

A help file is an html file. Each of the topics is indexed with an anchor

The end of the topics is recognised when there is the next topics, i.e., another anchor <a name="next topic"></a> You can link to such anchors, e.g. with <a href="#topics name">topics name</a>

Please, in links use as text the same name as the anchor, as it is used by the help system of SCIFF.