Invoking zdatrinf

 

The zdatrinf module represents the DATR inference engine and is mainly a collection of query-input handlers and a graph traversal algorithm. Given a DATR token file, the compiled theory is read into internal data structures.

The following command-line parameter are supported:

Obligatory

Parameter

-i FileName

The required file name of the DATR token file (generated by zdatrtok). The file name stdin accepts an input stream from the current terminal or Unix pipe.

Optional

Parameter

-t FileName

The optional trace file name. All output regarding traces and results of queries will be redirected from stdout to this file, except when using manual input. In the latter case, at least the results of the queries will be displayed on screen.

-v Number

The verbosity level of the programm, ranges from -2 (quiet) to 3 (chatter). Every higher level includes the previous one. In increasing detail:

(-2)

show only errors and results of queries (values), omit the final '.'

(-1)

with '.'

(0)

with full theorems

(1)

with traces including the number of used inferences

(2)

with used rules

(3)

with a complete scan of the input file (not recommended). When using zdatrinf in manual mode, the trace level can be changed anytime by entering trace X (X {-2,...,3}) instead of a query.

-u

Treatment of undefined paths. In the default case, evaluation halts and the programme exits with an error message. If the -u flag is set, evaluation continues and the null value is returned. Note that returning a value such as '!_UNDEFINED_!' for undefined paths is equivalent to including the equation <>=='!\_UNDEFINED\_!' at all nodes which have no definition for the empty LHS path.

-m Number

Maximum depth of query inference recursion (default 200). While evaluating an equation, only this number of further subcalls to the query engine will be supported. Depending on the design of the given theory, circular inferences may occur. The programm will force a break if the specified maximum recursion depth is exceeded. When a forced break occurs, the queried equation will return the empty atom, and an error message will be written to the error file.

-r Number

Maximum number of recursions for nested paths (Default 100). Similar to the problem above, paths within paths will be evaluated only up to this recursion depth.

-c

Crunch the output. By default all result atoms will be separated with a single SPACE; the -c option suppresses this separation.

Input specification

Queries can be given in three different ways, via manual input, via query list file and via query declaration file. The types can be mixed in any order. If none of these is given, manual input is presumed.

-k

additional manual input via keyboard

-q FileName

input of a query list file. The query file contains the same kind of input which could be given via keyboard, just listed in a file.

-d FileName

input of a query declaration file. The declaration file contains a # hide list of nodes that should not be queried (i.e. all not mentionend nodes will be used), and a list of # show and # showif paths to apply to these nodes for evaluation. The # hide declaration is optional, but at least one of the show or showif declarations must be present.