FuzzyCLIPS 6.42a

Fuzzy logic and certainty factor extensions for CLIPS 6.42

FuzzyCLIPS is a fuzzy logic extension of the CLIPS (C Language Integrated Production System) expert system shell from NASA. It was originally developed by the Integrated Reasoning Group of the Institute for Information Technology of the National Research Council of Canada. It enhances CLIPS by providing a fuzzy reasoning capability that is fully integrated with CLIPS facts and the inference engine, allowing one to represent and manipulate fuzzy facts and rules.

This version merges the original FuzzyCLIPS fuzzy extensions (based on CLIPS 6.05/6.10, circa 1997–2004) onto the modern CLIPS 6.42 codebase (released 2025), bringing the fuzzy and certainty-factor capabilities forward by roughly 20 years of CLIPS core improvements.

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Merge Strategy

The merge used CLIPS 6.42 as the base with the FuzzyCLIPS extensions ported on top. This was necessary because the two codebases diverged enormously between CLIPS 6.05 and 6.42 — essentially every API, data structure, and calling convention changed.

Key API Differences Bridged

Aspect	Original FuzzyCLIPS (6.05)	Merged FuzzyCLIPS (6.42)
Function style	globle / LOCALE / VOID macros	Standard C99 types
Environment	No Environment * parameter	All functions take Environment *
UDF registration	DefineFunction2()	AddUDF() with type codes bdefilmnsyv*;
Data types	DATA_OBJECT	CLIPSValue / UDFValue / UDFContext
Output	PrintRouter()	WriteString()
Memory	gm2() / rm()	genalloc() / genfree()
Boolean	int with TRUE/FALSE	<stdbool.h> bool / true / false

Files Modified from CLIPS 6.42 Base

The following CLIPS 6.42 core files were modified to integrate fuzzy support:

• setup.h — Added FUZZY_DEFTEMPLATES (default 1) and CERTAINTY_FACTORS (default 1) compile-time flags. Updated banner to "FuzzyCLIPS (6.42a 02/26/26)".
• constant.h — Added FUZZY_VALUE_TYPE (10), FUZZY_VALUE_BIT, and fuzzy function type constants (S_FUNCTION, Z_FUNCTION, PI_FUNCTION, etc.).
• entities.h — Added CLIPSFuzzyValue struct (with TypeHeader, reference count, and struct fuzzy_value *contents). Added fuzzyValue member to the CLIPSValue and UDFValue unions.
• symbol.h — Added fuzzy value hash table pointer to symbolData, plus declarations for AddFuzzyValue, RetainFuzzyValue, ReleaseFuzzyValue, GetFuzzyValueTable, and SetFuzzyValueTable.
• symbol.c — Implemented the fuzzy value hash table functions listed above, guarded by #if FUZZY_DEFTEMPLATES.
• tmpltdef.h — Added fuzzyTemplate bitfield and fuzzyList pointer to the Deftemplate struct, plus #include "fuzzylv.h".
• tmpltdef.c — Added calls to InitializeFuzzy(theEnv) and InitializeCF(theEnv) in the deftemplate initialization path, guarded by the respective compile-time flags.
• factmngr.h — Added double certaintyFactor field to the Fact struct, guarded by #if CERTAINTY_FACTORS.

New Fuzzy Extension Files

These files were created to implement the fuzzy/CF extensions:

File	Purpose
fuzzyval.h	Core struct fuzzy_value definition (x/y arrays, name, etc.)
fuzzylv.h	struct fuzzyLv — fuzzy linguistic variable (universe of discourse, primary terms)
fuzzydef.h / fuzzydef.c	InitializeFuzzy() — bootstrap entry point; initializes modifiers, S/Z/PI curves
fuzzycom.h / fuzzycom.c	DeffuzzyCommands() — registers ~25 fuzzy UDF commands (defuzzify, get-u, get-fs, fuzzy-union/intersection/modify, inference type, display precision, alpha value, etc.)
fuzzyutl.h / fuzzyutl.c	Utility functions: FZ_EQUAL, fcompliment, PrintFuzzySet, funion, fintersect
fuzzypsr.h / fuzzypsr.c	Fuzzy parser: Init_S_Z_PI_yvalues (precomputed S/Z/PI curves), sFunction, ParseFuzzyTemplate, InstallFuzzyValue/DeinstallFuzzyValue
fuzzylhs.h / fuzzylhs.c	LHS fuzzy pattern matching: GetFuzzyLHSPattern
fuzzyrhs.h / fuzzyrhs.c	RHS fuzzy value handling: CopyFuzzyValue, CompactFuzzyValue, ParseAssertFuzzyFact
fuzzymod.h / fuzzymod.c	Fuzzy modifiers (hedges): very, somewhat, more-or-less, slightly, etc. via concentrateFuzzyValue, dilateFuzzyValue, intensifyFuzzyValue, modifyFuzzyValue
cfdef.h / cfdef.c	Certainty factors: InitializeCF(), get-threshold/set-threshold/unthreshold/get-cf, combineCF formula, enable-rule-cf-calculation/disable-rule-cf-calculation

Implementation Status

Feature	Status
Core CLIPS 6.42 engine	Fully functional
Fuzzy UDF command registration	Fully functional (25+ commands)
Certainty factor commands	Fully functional (get-cf, set-threshold, unthreshold, etc.)
Fuzzy inference type get/set	Fully functional (max-min, max-prod)
Display precision / alpha value	Fully functional
Fuzzy modifier (hedge) framework	Fully functional (not, very, somewhat, extremely, etc.)
Fuzzy deftemplate parsing	Fully functional (universe, primary terms, S/Z/PI, singletons)
Fuzzy LHS/RHS pattern matching	Fully functional (linguistic expressions, modifiers, AND/OR)
Fuzzy set operations (union/intersection)	Fully functional (funion, fintersect, maxmin_intersect)
Defuzzification (moment/maximum)	Fully functional (moment-defuzzify, maximum-defuzzify)
Fuzzy value UDF accessors	Fully functional (get-u, get-fs, create-fuzzy-value, etc.)
Fuzzy union/intersection/modify UDFs	Fully functional
Plot fuzzy value	Fully functional (text-based plot)

Note: The core fuzzy reasoning algorithms have been ported from the original FuzzyCLIPS source (CLIPS 6.05 era) to the modern CLIPS 6.42 API. The rule-engine integration functions (computeFuzzyConsequence, changeValueOfFuzzySlots) remain as documented stubs pending deeper integration with the 6.42 rule engine internals.

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Prerequisites

• GCC (or compatible C99 compiler)
• GNU Make
• Linux / WSL (tested on Ubuntu under WSL2)

Building

cd /home/jovan/devel/Clips_code/FuzzyCLIPS_merged
make clean
make -j$(nproc)

This produces:

• fuzzyclips — the interactive console binary
• libclips.a — static library

Build Options

The makefile uses these defaults:

CC = gcc
CFLAGS = -std=c99 -O3 -fno-strict-aliasing -Wall ...

To build in debug mode, edit the makefile or override:

make CFLAGS="-std=c99 -O0 -g -DLINUX"

To disable fuzzy or CF extensions at compile time, edit setup.h:

#define FUZZY_DEFTEMPLATES 0   /* disable fuzzy support */
#define CERTAINTY_FACTORS  0   /* disable CF support */

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Running FuzzyCLIPS

Interactive Mode

./fuzzyclips

You'll see the prompt:

     FuzzyCLIPS (6.42a 02/26/26)
FuzzyCLIPS>

Batch Mode

./fuzzyclips -f myscript.clp

Quick Fuzzy Command Examples

FuzzyCLIPS> (get-fuzzy-inference-type)
max-min
FuzzyCLIPS> (set-fuzzy-inference-type max-prod)
FuzzyCLIPS> (get-fuzzy-inference-type)
max-prod
FuzzyCLIPS> (get-fuzzy-display-precision)
4
FuzzyCLIPS> (get-threshold)
0.0
FuzzyCLIPS> (set-threshold 0.3)
FuzzyCLIPS> (get-threshold)
0.3
FuzzyCLIPS> (assert (my-fact 42))
<Fact-1>
FuzzyCLIPS> (get-cf 1)
1.0

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Unit Tests

The tests/ directory contains 5 test suites with 64 test cases covering core CLIPS functionality and the fuzzy/CF extensions.

Test Suites

File	Tests	Description
test_01_basic.clp	21	Math, strings, type predicates, lists, fact system
test_02_rules.clp	6	Rule firing, salience, pattern matching, rule chaining
test_03_fuzzy_commands.clp	13	Fuzzy inference type, display precision, alpha value, CF threshold, UDF registration
test_04_certainty_factors.clp	6	get-cf, set-threshold, unthreshold, rule-based CF
test_05_constructs.clp	18	Deftemplate, deffacts, defglobal, deffunction, defrule, modify, query functions

Running All Tests

bash tests/run_all_tests.sh

Expected output:

============================================
 FuzzyCLIPS Unit Test Runner
 ...
============================================

Running: test_01_basic.clp
--------------------------------------------
  PASS: addition 2+3=5
  ...
  => SUITE PASSED (21 passed)

...

============================================
 OVERALL RESULTS
============================================
 Test suites: 5 passed, 0 failed
 Test cases:  64 passed, 0 failed
============================================

ALL SUITES PASSED

Running a Single Test

./fuzzyclips -f tests/test_03_fuzzy_commands.clp

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Directory Structure

FuzzyCLIPS_merged/
├── README.md              # This file
├── makefile               # Build system
├── main.c                 # Entry point
├── fuzzyclips             # Built binary
├── libclips.a             # Built static library
├── setup.h                # Compile-time config (FUZZY_DEFTEMPLATES, CERTAINTY_FACTORS)
├── *.c / *.h              # CLIPS 6.42 core source (~167 files)
├── fuzzyval.h             # Fuzzy value struct definition
├── fuzzylv.h              # Fuzzy linguistic variable struct
├── fuzzydef.c/h           # Fuzzy initialization
├── fuzzycom.c/h           # Fuzzy UDF commands (~25 registered)
├── fuzzyutl.c/h           # Fuzzy utility functions
├── fuzzypsr.c/h           # Fuzzy parser, S/Z/PI curves
├── fuzzylhs.c/h           # Fuzzy LHS pattern matching
├── fuzzyrhs.c/h           # Fuzzy RHS value handling
├── fuzzymod.c/h           # Fuzzy modifiers (hedges)
├── cfdef.c/h              # Certainty factor commands
└── tests/
    ├── run_all_tests.sh   # Test runner script
    ├── test_01_basic.clp
    ├── test_02_rules.clp
    ├── test_03_fuzzy_commands.clp
    ├── test_04_certainty_factors.clp
    └── test_05_constructs.clp

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Origins

• CLIPS 6.42 — https://clipsrules.net — Gary Riley, released 2025
• FuzzyCLIPS — Bob Orchard, NRC Canada (National Research Council) — integrated fuzzy reasoning for CLIPS 6.05/6.10
• This merge — February 2026, porting FuzzyCLIPS extensions onto the CLIPS 6.42 codebase

License

CLIPS is public domain software. The FuzzyCLIPS extensions follow the same terms.