The sgp command (for Set/Show Global Parameters) is used to query and set the value of global parameters and toggle traces, both interactively and in model files. This is the syntax for its use:
(Sgp {{:parameter value}* | {:parameter}*})
To
print and return the value of some but not all parameters, sgp can be called with just the
list of those parameter keywords. For
example, to print the value of G and
Conflict Resolution Trace one would
execute (sgp :g :crt). That will print the specified
parameters and also return the list of their values.
To set global parameters and traces, call the sgp command with the series of parameter keywords followed by the desired value. For example, to set the Goal value G to 10.0 and to turn Activation Trace on call (sgp :g 10.0 :act t). In general, sgp will check that the values supplied fall within the required type and range for the parameter, and reject those that don't while printing a warning message.
For the switches, a value of NIL means that the function corresponding to the parameter is disabled. A value of T means that it is enabled. Other types of values that are acceptable for parameters are detailed with the parameters. Note that values are set as specified and are NOT evaluated.
Here are all of the global parameters which can be queried or set with sgp. They are detailed in the order that they are displayed by the no parameter form of sgp and the names of the sections are indicated.
Enable Subsymbolic Computations
keyword:
ESC or ERA default
value: NIL
Enables the subsymbolic computations for activation
and expected gain. This was formerly
know as the Enable Rational Analysis parameter and can still be set with the
ERA keyword, but its use is deprecated.
G
keyword: G default
value: 20.0
The value of G in the PG-C
evaluation Must be a positive number.
Expected Gain S
keyword:
EGS default
value: NIL
If enabled, the S-value of the
Gaussian noise added to the PG-C
evaluation for each instantiation Must be a positive number. The variance of the noise can be set or accessed
as EGN.
Enable Randomness
keyword: ER default
value: NIL
If enabled, ties among instantiations are broken randomly, rather than
according to some unspecified but deterministic order.
Utility Threshold
keyword: UT default
value: 0.0
The threshold for the utility of a production below which it will not be
considered during conflict resolution.
Setting it to NIL is equivalent to disabling the threshold, i.e.
considering all productions.
Goal Activation
keyword: GA default
value: 1.0
The total level of source activation, i.e. the Wj. That level is divided evenly among chunks in
the slot values of the current chunk in the goal buffer. Must be a positive number.
Base Level Constant
keyword:
BLC default
value: 0.0
A constant added to all chunk base levels.
Can be any number.
Activation Noise S
keyword:
ANS default
value: NIL
If enabled, the S-value of the
Gaussian noise added to each chunk activation at every cycle. Must be a positive number. The variance of the noise can be accessed or
set as AN.
Permanent Activation
Noise S
keyword: PAS default
value: NIL
If enabled, the S-value of the
Gaussian noise added to each chunk activation at creation. Must be a positive number. The variance of the noise can be accessed or
set as PAN.
Latency Factor
keyword: LF default
value: 1.0
The multiplicative factor F in the
latency equation. Must
be a positive number.
Latency Exponent
keyword: LE default
value: 1.0
The exponent factor f in the
latency equation. Must
be a positive number. [This parameter has been deprecated as of ACT-R 5
and is not shown in the latency equation in the tutorial.]
Default Action Time
keyword:
DAT default
value: 0.05
The default action time of a production, i.e. the time between selection
and firing. Must be a
positive number, usually interpreted in milliseconds.
Partial Matching
keyword: PM default
value: NIL
Enables partial matching.
Mismatch Penalty
keyword: MP default
value: 1.0
This is the match scale parameter P in the activation equation. Must be a positive number.
Maximum Similarity
keyword: MS default
value: 0.0
This is the maximum similarity that can exist between any two chunks. It is the value of a perfect match and is the
default similarity between a chunk and itself.
Must be a number.
Maximum Difference
keyword: MD default
value: -1.0
This is the minimum similarity that can exist between any two chunks. It is the value of a perfect mismatch and is
the default similarity between a chunk and any chunk other than itself. Must be a number, and should always be less
than or equal to the Maximum similarity but that is currently not enforced by
the system.
Maximum Associative
Strength
keyword: MAS default
value: NIL
When enabled, it is used as the S value in the Sji
calculation. It is the theoretical maximum
associative strength a chunk could have if it has no associations. This replaces the need to set the internal *wme-number* variable as was done in ACT-R 4 and before.]
Retrieval Threshold
keyword: RT default
value: NIL
When enabled, chunks with activation levels below this threshold cannot be
retrieved. Works with
both partial and exact (standard) matching.
Temperature
keyword:
TMP default
value: 1.0
When blending is enabled this parameter is used as the scaling factor. It must be a positive number.
Blending
keyword:
BLN default
value: NIL
When enabled turns on the blending mechanism in ACT-R. Blending is a mechanism that allows for
aggregate retrievals. That is, a
retrieval request will return a chunk which is not necessarily a specific
instance of a chunk from declarative memory, but a weighted aggregation of all
the chunks that could be matches.
Optimized Learning
keyword: OL default
value: T
If enabled, an efficient approximation to the formulas for base level
learning is used. May
also be set to a positive integer. When it has a numerical value, then a
hybrid optimization calculation occurs for base levels. That hybrid calculation is a combination of
the specified number of exact presentations in conjunction with the optimized
equation for all prior to that subset.
Base Level Learning
keyword:
BLL default
value: NIL
If enabled, used as d in the
equation for learning the base level activations of chunks. Must be a positive number, with 0.5 the
standard value.
Associative Learning
keyword:
If enabled, used as assoc in the
posterior strength equation for learning
the associative strength between pairs of chunks. Must be a positive number.
Strength Learning
keyword: SL default
value: NIL
If enabled, used as d in the
equation for learning the strength of productions. Must be a positive number,
preferably less than 1.0.
Production strengths are deprecated in ACT-R 5.
Parameters Learning
keyword: PL default
value: NIL
If enabled, the parameters p and q will
be learned for each production. Can also be set to the decay rate for use in the discounting
version of learning equations.
Cost Penalty
keyword: CP default
value: 1.0
When production compilation is enabled, this is the value of the K
parameter which is the penalty added to the cost of newly created
productions. Must be
any number.
Initial Experience
keyword: IE default
value: 10.0
When production compilation is enabled, this is the value of the a parameter which is used to compute the
successes and failures of the newly created productions. Must be any number.
Threshold Time
keyword: TT default
value: 2.0
When production compilation is enabled, this parameter sets the maximum
amount of time that can pass between two productions and still allow them to be
compiled together. Must
be a positive number.
Enable Production
Learning
keyword:
EPL default
value: NIL
This switch enables the production learning (compilation) mechanism.
These traces are enumerated here roughly in the order they would appear during each production cycle. They can be enabled by being set to T, which sends the trace output to the standard output (Lisp listener), or to any file name, pathname or stream if output is to be directed to another destination.
Exact Matching Trace
keyword:
EMT default
value: NIL
If enabled, prints a message during production matching every time a condition
is evaluated.
Partial Matching
Trace
keyword:
PMT default
value: NIL
If enabled, prints messages detailing retrieval requests when Partial Matching is enabled.
Production
Compilation Trace
keyword:
PCT default
value: T
If enabled, prints the main steps of the production compilation process.
Activation Trace
keyword:
ACT default
value: NIL
If enabled, prints a trace of the main steps during computation of chunk
activation on a retrieval request.
Blending Trace
keyword:
BLT default
value: NIL
If enabled, prints messages detailing blending during retrieval requests when
blending is enabled.
Conflict Resolution
Trace
keyword:
CRT default
value: NIL
If enabled, prints the name of each production as it is matched curing conflict
resolution.
Conflict Set Trace
keyword:
CST default
value: NIL
If this option is enabled, prints the number of instantiations in the conflict set, and,
when subsymbolic computations are enabled, the number
of instantiations that were considered and the expected gain of the
instantiation that will fire.
Matches Trace
keyword: MT default
value: NIL
If enabled, prints all the instantiations generated. A setting of SHORT will simply print the list
of variables and their values for each instantiation, and a setting of T will
print the whole production(s) with the variables replaced by their values.
Production Trace
keyword: PT default
value: NIL
If enabled, prints the selected production instantiation before firing it. A setting of SHORT will simply print the list
of variables and their values, and a setting of T will print the whole
production with the variables replaced by their values.
Cycle Trace
keyword: CT default
value: T
If enabled, prints the current time and name of production upon selection and
firing.
Latency Trace
keyword: LT default
value: T
If enabled, prints the latency of the
action side of the production.
Output Trace
keyword: OT default
value: T
If enabled, prints the output of !output!
commands on the right-hand side of productions.
Declarative Memory
Trace
keyword:
DMT default
value: NIL
If enabled, prints a message when a chunk is created, deleted or modified.
Goal Trace
keyword: GT default
value: NIL
If enabled, prints a message when either a new chunk is placed into the goal
buffer (a +goal request) or the goal buffer is cleared (a –goal request).
Verbose
keyword: V default
value: T
If enabled, the traces are printed as enabled.
If disabled, turns off all trace output regardless of which are enabled. Disabling
this trace is useful to easily turn off all trace output when running in batch
mode where performance is key.