smem¶
Controls the behavior of and displays information about semantic memory.
Synopsis¶
=======================================================
- Semantic Memory Sub-Commands -
=======================================================
smem [? | help] Print help screen
smem [--enable | --disable ] Turn smem on/off
smem [--get | --set] <option> [<value>] Print or set a parameter
smem --add { (id ^attr value)* } Add memory to smem
smem --backup <filename> Save copy of database
smem --clear Delete contents of smem
smem --export <filename> [<LTI>] Save database to file
smem --init Reinit smem store
smem --query {(cue)* [<num>]} Query smem via given cue
smem --remove { (id [^attr [value]])* } Remove smem structures
------------------------ Printing ---------------------
print @ Print all smem contents
print <LTI> Print specific smem memory
smem --history <LTI> Print memory activation history
=======================================================
- Semantic Memory Parameters (use --set) -
=======================================================
enabled off
database [ MEMORY | file ] Store database in memory or file
append on Append or overwrite after init
path Path to database on disk
---------------------- Activation ---------------------
activation-mode [ RECENCY | frequency | base-level ]
activate-on-query [ ON | off ]
base-decay 0.5 Decay amount for base-level activation
base-update-policy [ STABLE | naive | incremental ]
base-incremental-threshes 10 Integer > 0
thresh 100 Integer >= 0
base-inhibition [ on | OFF ]
---------- Experimental Spreading Activation ----------
spreading [ on | OFF ]
spreading-limit 300 integer > 0
spreading-depth-limit 10 integer > 0
spreading-baseline 0.0001 1 > decimal > 0
spreading-continue-probability 0.9 1 > decimal > 0
spreading-loop-avoidance [ on | OFF ]
spreading-edge-updating [ on | OFF ]
spreading-wma-source [ on | OFF ]
spreading-edge-update-factor 0.99 1 > decimal > 0
------------- Database Optimization Settings ----------
lazy-commit on Delay writing store until exit
optimization [ safety | PERFORMANCE ]
cache-size 10000 Number of memory pages for SQLite cache
page-size 8k Size of each memory page
----------------- Timers and Statistics ---------------
timers [ OFF | one | two | three ] How detailed timers should be
smem --timers [<timer>] Print summary or specifics
smem --stats [<stat>] Print summary or specifics
---------------------
Timers: smem_api, smem_hash, smem_init, smem_query,
smem_ncb_retrieval, three_activation
smem_storage, _total
Stats: act_updates, db-lib-version, edges, mem-usage,
mem-high, nodes, queries, retrieves, stores
-------------------------------------------------------
For a detailed explanation of these settings: help smem
Summary Output¶
With no arguments, smem will return a quick summary of key aspects of semantic
memory.
====================================================
Semantic Memory Summary
====================================================
Enabled off
Storage Memory (append after init)
----------------------------------------------------
Nodes 2
Edges 1
Memory Usage 406784 bytes
----------------------------------------------------
For a full list of smem's sub-commands and settings: smem ?
Options¶
| Commands | Description |
|---|---|
-e, --enable, --on |
Enable semantic memory. |
-d, --disable, --off |
Disable semantic memory. |
-g, --get |
Print current parameter setting |
-s, --set |
Set parameter value |
-c, --clear |
Deletes all memories |
-x, --export |
Creates an agent-sourceable copy of semantic memory on disk |
-i, --init |
Deletes all memories if append is off |
-S, --stats |
Print statistic summary or specific statistic |
-t, --timers |
Print timer summary or specific statistic |
-a, --add |
Add concepts to semantic memory |
-r, --remove |
Remove concepts from semantic memory |
-q, --query |
Print concepts in semantic store matching some cue |
-h, --history |
Print activation history for some LTI |
-b, --backup |
Creates a backup of the semantic database on disk |
Printing¶
To print from semantic memory, the standard print command can be used, for example, to print a specific LTI:
p @23
To print the entire semantic store:
p @
Note that such print commands will honor the --depth parameter passed in.
The command trace --smem displays additional trace information for semantic
memory not controlled by this command.
Parameters¶
Due to the large number of parameters, the smem command uses the --get|--set
<parameter> <value> convention rather than individual switches for each
parameter. Running smem without any switches displays a summary of the
parameter settings.
| Parameter | Description | Possible values | Default |
|---|---|---|---|
append |
Controls whether database is overwritten or appended when opening or re-initializing | on, off |
off |
database |
Database storage method | file, memory |
memory |
learning |
Semantic memory enabled | on, off |
off |
path |
Location of database file | empty, some path | empty |
The learning parameter turns the semantic memory module on or off. This is the
same as using the enable and disable commands.
The path parameter specifies the file system path the database is stored in.
When path is set to a valid file system path and database mode is set to file,
then the SQLite database is written to that path.
The append parameter will determine whether all existing facts stored in a
database on disk will be erased when semantic memory loads. Note that this
affects semantic memory re-initialization also, i.e. if the append setting is
off, all semantic facts stored to disk will be lost when a soar init is
performed. For semantic memory,
append mode is by default on.
Note that changes to database, path and append will not have an effect until
the database is used after an initialization. This happens either shortly after
launch (on first use) or after a database initialization command is issued. To
switch databases or database storage types while running, set your new
parameters and then perform an smem --init command.
Activation Parameters¶
| Parameter | Description | Possible values | Default |
|---|---|---|---|
| activation-mode | Sets the ordering bias for retrievals that match more than one memory | recency, frequency, base-level |
recency |
| activate-on-query | Determines if the results of queries should be activated | on, off |
on |
| base-decay | Sets the decay parameter for base-level activation computation | > 0 |
0.5 |
| base-update-policy | Sets the policy for re-computing base-level activation | stable, naive, incremental |
stable |
| base-incremental-threshes | Sets time deltas after which base-level activation is re-computed for old memories | 1, 2, 3, ... | 10 |
| thresh | Threshold for activation locality | 0, 1, ... | 100 |
| base-inhibition | Sets whether or not base-level activation has a short-term inhibition factor. | on, off |
off |
If activation-mode is base-level, three parameters control bias values. The
base-decay parameter sets the free decay parameter in the base-level model.
Note that we do implement the (Petrov, 2006) approximation, with a history size
set as a compile-time parameter (default=10). The base-update-policy sets the
frequency with which activation is recomputed. The default, stable, only
recomputes activation when a memory is referenced (through storage or
retrieval). The naive setting will update the entire candidate set of memories
(defined as those that match the most constraining cue WME) during a retrieval,
which has severe performance detriment and should be used for experimentation or
those agents that require high-fidelity retrievals. The incremental policy
updates a constant number of memories, those with last-access ages defined by
the base-incremental-threshes set. The base-inhibition parameter switches an
additional prohibition factor on or off.
Performance Parameters¶
| Parameter | Description | Possible values | Default |
|---|---|---|---|
| cache-size | Number of memory pages used in the SQLite cache | 1, 2, ... | 10000 |
| lazy-commit | Delay writing semantic store changes to file until agent exits | on, off |
on |
| optimization | Policy for committing data to disk | safety, performance |
performance |
| page-size | Size of each memory page used in the SQLite cache | 1k, 2k, 4k, 8k, 16k, 32k, 64k | 8k |
| timers | Timer granularity | off, one, two, three |
off |
When the database is stored to disk, the lazy-commit and optimization
parameters control how often cached database changes are written to disk. These
parameters trade off safety in the case of a program crash with database
performance. When optimization is set to performance, the agent will have an
exclusive lock on the database, meaning it cannot be opened concurrently by
another SQLite process such as SQLiteMan. The lock can be relinquished by
setting the database to memory or another database and issuing init-soar/smem
--init or by shutting down the Soar kernel.
Statistics¶
Semantic memory tracks statistics over the lifetime of the agent. These can be
accessed using smem --stats <statistic>. Running smem --stats without a
statistic will list the values of all statistics. Unlike timers, statistics will
always be updated.
Available statistics are:
| Name | Label | Description |
|---|---|---|
act_updates |
Activation Updates | Number of times memory activation has been calculated |
db-lib-version |
SQLite Version | SQLite library version |
edges |
Edges | Number of edges in the semantic store |
mem-usage |
Memory Usage | Current SQLite memory usage in bytes |
mem-high |
Memory Highwater | High SQLite memory usage watermark in bytes |
nodes |
Nodes | Number of nodes in the semantic store |
queries |
Queries | Number of times the query command has been issued |
retrieves |
Retrieves | Number of times the retrieve command has been issued |
stores |
Stores | Number of times the store command has been issued |
Timers¶
Semantic memory also has a set of internal timers that record the durations of
certain operations. Because fine-grained timing can incur runtime costs,
semantic memory timers are off by default. Timers of different levels of detail
can be turned on by issuing smem --set timers <level>, where the levels can be
off, one, two, or three, three being most detailed and resulting in
all timers being turned on. Note that none of the semantic memory statistics nor
timing information is reported by the stats command.
All timer values are reported in seconds.
Level one
| Timer | Description |
|---|---|
_total |
Total smem operations |
Level two
| Timer | Description |
|---|---|
smem_api |
Agent command validation |
smem_hash |
Hashing symbols |
smem_init |
Semantic store initialization |
smem_ncb_retrieval |
Adding concepts (and children) to working memory |
smem_query |
Cue-based queries |
smem_storage |
Concept storage |
Level three
| Timer | Description |
|---|---|
| three_activation | Recency information maintenance |
smem --add¶
Concepts can be manually added to the semantic store using the smem --add
<concept> command. The format for specifying the concept is similar to that of
adding WMEs to working memory on the RHS of productions. For example:
smem --add {
(<arithmetic> ^add10-facts <a01> <a02> <a03>)
(<a01> ^digit1 1 ^digit-10 11)
(<a02> ^digit1 2 ^digit-10 12)
(<a03> ^digit1 3 ^digit-10 13)
}
Although not shown here, the common "dot-notation" format used in writing productions can also be used for this command. Unlike agent storage, manual storage is automatically recursive. Thus, the above example will add a new concept (represented by the temporary "arithmetic" variable) with three children. Each child will be its own concept with two constant attribute/value pairs.
smem --remove¶
Part or all of the information in the semantic store of some LTI can be manually removed from the semantic store using the
command. The format for specifying what to remove is similar to that of adding WMEs to working memory on the RHS of productions. For example:
If good-attribute is multi-valued, then all values will remain in the store
except |gibberish value|. If |gibberish value| is the only value, then
good-attribute will also be removed. It is not possible to use the common
"dot-notation" for this command. Manual removal is not recursive.
Another example highlights the ability to remove all of the values for an attribute:
When a value is not given, all of the values for the given attribute are removed from the LTI in the semantic store.
Also, it is possible to remove all augmentations of some LTI from the semantic store:
This would remove all attributes and values of @34 from the semantic store.
The LTI will remain in the store, but will lack augmentations.
(Use the following at your own risk.) Optionally, the user can force removal even in the event of an error:
Suppose that LTI @34 did not contain bad-attribute. The above example would
remove bad-attribute-2 even though it would indicate an error (having not
found bad-attribute).
smem --query¶
Queries for LTIs in the semantic store that match some cue can be initialized
external to an agent using the smem --query <cue> [<num>] command. The format
for specifying the cue is similar to that of adding a new identifier to working
memory in the RHS of a rule:
Note that the root of the cue structure must be a variable and should be unused in the rest of the cue structure. This command is for testing and the full range of queries accessible to the agent are not yet available for the command. For example, math queries are not supported.
The additional option of <num> will trigger the display of the top <num>
most activated LTIs that matched the cue.
The result of a manual query is either to print that no LTIs could be found or
to print the information associated with LTIs that were found in the print
<lti> format.
smem --history¶
When the activation-mode of a semantic store is set to base-level, some history of activation events is stored for each LTI. This history of when some LTI was activated can be displayed:
In the event that semantic memory is not using base-level activation, history
will mimic print.
Experimental Spreading Activation¶
| Parameter | Description | Possible values | Default |
|---|---|---|---|
| spreading | Controls whether spreading activation is on or off. | on, off |
off |
| spreading-limit | Limits amount of spread from any LTI | 0, 1, ... | 300 |
| spreading-depth-limit | Limits depth of spread from any LTI | 0, 1, ..., 10 | 10 |
| spreading-baseline | Gives minimum to spread values. | 0, ..., 1 | 0.0001 |
| spreading-continue-probability | Gives 1 - (decay factor of spread with distance) | 0, ..., 1 | 0.9 |
| spreading-loop-avoidance | Controls whether spread traversal avoids self-loops | on, off |
off |
Spreading activation has been added as an additional mechanism for ranking LTIs
in response to a query. Spreading activation is only compatible with base-level
activation. activation-mode must be set to base-level in order to also use
spreading. They are additive. Spreading activation serves to rank LTIs that are
connected to those currently instanced in Working Memory more highly than those
which are unconnected. Note that spreading should be turned on before running an
agent. Also, be warned that an agent which loads a database with spreading
activation active at the time of back-up currently has undefined behavior and
will likely crash as spreading activation currently maintains state in the
database.
Spreading activation introduces additional parameters. spreading-limit is an
absolute cap on the number of LTIs that can receive spread from a given
instanced LTI. spreading-depth-limit is an absolute cap on the depth to which
a Working Memory instance of some LTI can spread into the SMem network.
spreading-baseline provides a minimum amount of spread that an element can
receive. spreading-continue-probability sets the amount of spread that is
passed on with greater depth. (It can also be thought of as 1-decay where decay
is the loss of spread magnitude with depth.) spreading-loop-avoidance is a
boolean parameter which controls whether or not any given spread traversal can
loop back onto itself.
Note that the default settings here are not necessarily appropriate for your application. For many applications, simply changing the structure of the network can yield wildly different query results even with the same spreading parameters.