477 lines
18 KiB
Plaintext
477 lines
18 KiB
Plaintext
{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {
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"collapsed": true
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},
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"source": [
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"# Implementeren van een Expert Systeem voor Dieren\n",
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"\n",
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"Een voorbeeld uit de [AI for Beginners Curriculum](http://github.com/microsoft/ai-for-beginners).\n",
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"\n",
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"In dit voorbeeld implementeren we een eenvoudig kennisgebaseerd systeem om een dier te bepalen op basis van enkele fysieke kenmerken. Het systeem kan worden weergegeven door de volgende AND-OR-boom (dit is een deel van de hele boom, we kunnen gemakkelijk meer regels toevoegen):\n",
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"\n",
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"\n"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Onze eigen expert systeemomgeving met achterwaartse inferentie\n",
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"\n",
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"Laten we proberen een eenvoudige taal te definiëren voor kennisrepresentatie gebaseerd op productieregels. We zullen Python-klassen gebruiken als sleutelwoorden om regels te definiëren. Er zijn in wezen 3 soorten klassen:\n",
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"* `Ask` vertegenwoordigt een vraag die aan de gebruiker gesteld moet worden. Het bevat de set mogelijke antwoorden.\n",
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"* `If` vertegenwoordigt een regel, en het is slechts syntactische suiker om de inhoud van de regel op te slaan\n",
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"* `AND`/`OR` zijn klassen om AND/OR-takken van de boom te vertegenwoordigen. Ze slaan gewoon de lijst met argumenten binnenin op. Om de code te vereenvoudigen, is alle functionaliteit gedefinieerd in de bovenliggende klasse `Content`\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"metadata": {
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"trusted": true
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},
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"outputs": [],
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"source": [
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"class Ask():\n",
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" def __init__(self,choices=['y','n']):\n",
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" self.choices = choices\n",
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" def ask(self):\n",
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" if max([len(x) for x in self.choices])>1:\n",
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" for i,x in enumerate(self.choices):\n",
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" print(\"{0}. {1}\".format(i,x),flush=True)\n",
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" x = int(input())\n",
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" return self.choices[x]\n",
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" else:\n",
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" print(\"/\".join(self.choices),flush=True)\n",
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" return input()\n",
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"\n",
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"class Content():\n",
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" def __init__(self,x):\n",
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" self.x=x\n",
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" \n",
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"class If(Content):\n",
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" pass\n",
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"\n",
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"class AND(Content):\n",
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" pass\n",
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"\n",
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"class OR(Content):\n",
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" pass"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"In ons systeem zou het werkgeheugen de lijst van **feiten** bevatten als **attribuut-waardeparen**. De kennisbasis kan worden gedefinieerd als één groot woordenboek dat acties (nieuwe feiten die in het werkgeheugen moeten worden ingevoerd) afbeeldt op voorwaarden, uitgedrukt als AND-OR expressies. Ook kunnen sommige feiten worden `gevraagd` (`Ask`).\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"metadata": {
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"trusted": true
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},
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"outputs": [],
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"source": [
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"rules = {\n",
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" 'default': Ask(['y','n']),\n",
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" 'color' : Ask(['red-brown','black and white','other']),\n",
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" 'pattern' : Ask(['dark stripes','dark spots']),\n",
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" 'mammal': If(OR(['hair','gives milk'])),\n",
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" 'carnivor': If(OR([AND(['sharp teeth','claws','forward-looking eyes']),'eats meat'])),\n",
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" 'ungulate': If(['mammal',OR(['has hooves','chews cud'])]),\n",
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" 'bird': If(OR(['feathers',AND(['flies','lies eggs'])])),\n",
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" 'animal:monkey' : If(['mammal','carnivor','color:red-brown','pattern:dark spots']),\n",
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" 'animal:tiger' : If(['mammal','carnivor','color:red-brown','pattern:dark stripes']),\n",
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" 'animal:giraffe' : If(['ungulate','long neck','long legs','pattern:dark spots']),\n",
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" 'animal:zebra' : If(['ungulate','pattern:dark stripes']),\n",
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" 'animal:ostrich' : If(['bird','long nech','color:black and white','cannot fly']),\n",
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" 'animal:pinguin' : If(['bird','swims','color:black and white','cannot fly']),\n",
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" 'animal:albatross' : If(['bird','flies well'])\n",
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"}"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Om de backward inference uit te voeren, definiëren we de klasse `Knowledgebase`. Deze zal bevatten:\n",
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"* Werkend `memory` - een woordenboek dat attributen aan waarden koppelt\n",
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"* Knowledgebase `rules` in het hierboven gedefinieerde formaat\n",
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"\n",
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"Twee hoofdmethoden zijn:\n",
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"* `get` om de waarde van een attribuut te verkrijgen, waarbij indien nodig inferentie wordt uitgevoerd. Bijvoorbeeld, `get('color')` zou de waarde van een kleur-slot ophalen (het zal vragen indien nodig, en de waarde opslaan voor later gebruik in het werkgeheugen). Als we `get('color:blue')` vragen, zal het naar een kleur vragen en vervolgens een `y`/`n` waarde retourneren afhankelijk van de kleur.\n",
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"* `eval` voert de eigenlijke inferentie uit, dat wil zeggen, doorloopt AND/OR bomen, evalueert subdoelen, enz.\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 3,
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"metadata": {
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"trusted": true
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},
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"outputs": [],
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"source": [
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"class KnowledgeBase():\n",
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" def __init__(self,rules):\n",
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" self.rules = rules\n",
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" self.memory = {}\n",
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" \n",
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" def get(self,name):\n",
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" if ':' in name:\n",
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" k,v = name.split(':')\n",
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" vv = self.get(k)\n",
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" return 'y' if v==vv else 'n'\n",
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" if name in self.memory.keys():\n",
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" return self.memory[name]\n",
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" for fld in self.rules.keys():\n",
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" if fld==name or fld.startswith(name+\":\"):\n",
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" # print(\" + proving {}\".format(fld))\n",
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" value = 'y' if fld==name else fld.split(':')[1]\n",
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" res = self.eval(self.rules[fld],field=name)\n",
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" if res!='y' and res!='n' and value=='y':\n",
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" self.memory[name] = res\n",
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" return res\n",
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" if res=='y':\n",
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" self.memory[name] = value\n",
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" return value\n",
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" # field is not found, using default\n",
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" res = self.eval(self.rules['default'],field=name)\n",
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" self.memory[name]=res\n",
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" return res\n",
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" \n",
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" def eval(self,expr,field=None):\n",
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" # print(\" + eval {}\".format(expr))\n",
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" if isinstance(expr,Ask):\n",
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" print(field)\n",
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" return expr.ask()\n",
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" elif isinstance(expr,If):\n",
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" return self.eval(expr.x)\n",
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" elif isinstance(expr,AND) or isinstance(expr,list):\n",
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" expr = expr.x if isinstance(expr,AND) else expr\n",
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" for x in expr:\n",
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" if self.eval(x)=='n':\n",
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" return 'n'\n",
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" return 'y'\n",
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" elif isinstance(expr,OR):\n",
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" for x in expr.x:\n",
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" if self.eval(x)=='y':\n",
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" return 'y'\n",
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" return 'n'\n",
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" elif isinstance(expr,str):\n",
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" return self.get(expr)\n",
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" else:\n",
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" print(\"Unknown expr: {}\".format(expr))"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Laten we nu onze dierenkennisbasis definiëren en het consult uitvoeren. Let op dat deze oproep je vragen zal stellen. Je kunt antwoorden door `y`/`n` te typen voor ja-nee vragen, of door een nummer (0..N) op te geven voor vragen met langere meerkeuzeantwoorden.\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 4,
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"metadata": {
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"trusted": true
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"hair\n",
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"y/n\n",
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"sharp teeth\n",
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"y/n\n",
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"claws\n",
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"y/n\n",
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"forward-looking eyes\n",
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"y/n\n",
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"color\n",
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"0. red-brown\n",
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"1. black and white\n",
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"2. other\n",
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"has hooves\n",
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"y/n\n",
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"long neck\n",
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"y/n\n",
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"long legs\n",
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"y/n\n",
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"pattern\n",
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"0. dark stripes\n",
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"1. dark spots\n"
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]
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},
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{
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"data": {
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"text/plain": [
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"'giraffe'"
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]
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},
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"execution_count": 4,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"kb = KnowledgeBase(rules)\n",
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"kb.get('animal')"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Gebruik van Experta voor Voorwaartse Inferentie\n",
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"\n",
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"In het volgende voorbeeld zullen we proberen voorwaartse inferentie te implementeren met behulp van een van de bibliotheken voor kennisrepresentatie, [Experta](https://github.com/nilp0inter/experta). **Experta** is een bibliotheek voor het maken van voorwaartse inferentiesystemen in Python, die is ontworpen om vergelijkbaar te zijn met het klassieke oude systeem [CLIPS](http://www.clipsrules.net/index.html).\n",
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"\n",
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"We hadden ook zelf voorwaartse chaining kunnen implementeren zonder veel problemen, maar naïeve implementaties zijn meestal niet erg efficiënt. Voor effectievere regelmatching wordt een speciaal algoritme [Rete](https://en.wikipedia.org/wiki/Rete_algorithm) gebruikt.\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 5,
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"metadata": {
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"trusted": true
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Collecting git+https://github.com/nilp0inter/experta\n",
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" Cloning https://github.com/nilp0inter/experta to /tmp/pip-req-build-7qurtwk3\n",
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" Running command git clone --filter=blob:none --quiet https://github.com/nilp0inter/experta /tmp/pip-req-build-7qurtwk3\n",
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" Resolved https://github.com/nilp0inter/experta to commit c6d5834b123861f5ae09e7d07027dc98bec58741\n",
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" Installing build dependencies ... \u001b[?25ldone\n",
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"\u001b[?25h Getting requirements to build wheel ... \u001b[?25ldone\n",
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"\u001b[?25h Preparing metadata (pyproject.toml) ... \u001b[?25ldone\n",
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"\u001b[?25hRequirement already satisfied: frozendict~=2.4.6 in /opt/conda/envs/ai4beg/lib/python3.12/site-packages (from experta==1.9.5.dev1) (2.4.7)\n",
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"Collecting schema~=0.6.7 (from experta==1.9.5.dev1)\n",
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" Downloading schema-0.6.8-py2.py3-none-any.whl.metadata (14 kB)\n",
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"Downloading schema-0.6.8-py2.py3-none-any.whl (14 kB)\n",
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"Building wheels for collected packages: experta\n",
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" Building wheel for experta (pyproject.toml) ... \u001b[?25ldone\n",
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"\u001b[?25h Created wheel for experta: filename=experta-1.9.5.dev1-py3-none-any.whl size=34804 sha256=888c459512a5e713f4b674caa9a0f96cfdf07ec0d6eb56cc318ce0653d218014\n",
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" Stored in directory: /tmp/pip-ephem-wheel-cache-1eeii9zy/wheels/3d/e8/bb/22d7956359603fa8dd679aa09f5b8efb3f29991c3986fdc787\n",
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"Successfully built experta\n",
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"Installing collected packages: schema, experta\n",
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"\u001b[2K \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m2/2\u001b[0m [experta]\n",
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"\u001b[1A\u001b[2KSuccessfully installed experta-1.9.5.dev1 schema-0.6.8\n"
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]
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}
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],
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"source": [
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"import sys\n",
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"!{sys.executable} -m pip install git+https://github.com/nilp0inter/experta"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 13,
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"metadata": {
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"trusted": true
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},
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"outputs": [],
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"source": [
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"from experta import *\n",
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"#import experta"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"We definiëren ons systeem als een klasse die `KnowledgeEngine` als superklasse heeft. Elke regel wordt gedefinieerd door een aparte functie met de `@Rule`-annotatie, die specificeert wanneer de regel moet worden geactiveerd. Binnen de regel kunnen we nieuwe feiten toevoegen met de functie `declare`, en het toevoegen van die feiten zal ertoe leiden dat er meer regels worden aangeroepen door de voorwaartse inferentiemotor.\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 14,
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"metadata": {
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"trusted": true
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},
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"outputs": [],
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"source": [
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"class Animals(KnowledgeEngine):\n",
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" @Rule(OR(\n",
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" AND(Fact('sharp teeth'),Fact('claws'),Fact('forward looking eyes')),\n",
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" Fact('eats meat')))\n",
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" def cornivor(self):\n",
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" self.declare(Fact('carnivor'))\n",
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" \n",
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" @Rule(OR(Fact('hair'),Fact('gives milk')))\n",
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" def mammal(self):\n",
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" self.declare(Fact('mammal'))\n",
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"\n",
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" @Rule(Fact('mammal'),\n",
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" OR(Fact('has hooves'),Fact('chews cud')))\n",
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" def hooves(self):\n",
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" self.declare('ungulate')\n",
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" \n",
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" @Rule(OR(Fact('feathers'),AND(Fact('flies'),Fact('lays eggs'))))\n",
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" def bird(self):\n",
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" self.declare('bird')\n",
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" \n",
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" @Rule(Fact('mammal'),Fact('carnivor'),\n",
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" Fact(color='red-brown'),\n",
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" Fact(pattern='dark spots'))\n",
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" def monkey(self):\n",
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" self.declare(Fact(animal='monkey'))\n",
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"\n",
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" @Rule(Fact('mammal'),Fact('carnivor'),\n",
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" Fact(color='red-brown'),\n",
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" Fact(pattern='dark stripes'))\n",
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" def tiger(self):\n",
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" self.declare(Fact(animal='tiger'))\n",
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"\n",
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" @Rule(Fact('ungulate'),\n",
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" Fact('long neck'),\n",
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" Fact('long legs'),\n",
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" Fact(pattern='dark spots'))\n",
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" def giraffe(self):\n",
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" self.declare(Fact(animal='giraffe'))\n",
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"\n",
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" @Rule(Fact('ungulate'),\n",
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" Fact(pattern='dark stripes'))\n",
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" def zebra(self):\n",
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" self.declare(Fact(animal='zebra'))\n",
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"\n",
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" @Rule(Fact('bird'),\n",
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" Fact('long neck'),\n",
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" Fact('cannot fly'),\n",
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" Fact(color='black and white'))\n",
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" def straus(self):\n",
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" self.declare(Fact(animal='ostrich'))\n",
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"\n",
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" @Rule(Fact('bird'),\n",
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" Fact('swims'),\n",
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" Fact('cannot fly'),\n",
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" Fact(color='black and white'))\n",
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" def pinguin(self):\n",
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" self.declare(Fact(animal='pinguin'))\n",
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"\n",
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" @Rule(Fact('bird'),\n",
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" Fact('flies well'))\n",
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" def albatros(self):\n",
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" self.declare(Fact(animal='albatross'))\n",
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" \n",
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" @Rule(Fact(animal=MATCH.a))\n",
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" def print_result(self,a):\n",
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" print('Animal is {}'.format(a))\n",
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" \n",
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" def factz(self,l):\n",
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" for x in l:\n",
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" self.declare(x)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Zodra we een kennisbasis hebben gedefinieerd, vullen we ons werkgeheugen met enkele initiële feiten en roepen we vervolgens de methode `run()` aan om de inferentie uit te voeren. Je kunt zien dat als resultaat nieuwe afgeleide feiten worden toegevoegd aan het werkgeheugen, inclusief het uiteindelijke feit over het dier (als we alle initiële feiten correct hebben ingesteld).\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 15,
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"metadata": {
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"trusted": true
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Animal is tiger\n"
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]
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},
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{
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"data": {
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"text/plain": [
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"FactList([(0, InitialFact()),\n",
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" (1, Fact(color='red-brown')),\n",
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" (2, Fact(pattern='dark stripes')),\n",
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" (3, Fact('sharp teeth')),\n",
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" (4, Fact('claws')),\n",
|
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" (5, Fact('forward looking eyes')),\n",
|
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" (6, Fact('gives milk')),\n",
|
|
" (7, Fact('mammal')),\n",
|
|
" (8, Fact('carnivor')),\n",
|
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" (9, Fact(animal='tiger'))])"
|
|
]
|
|
},
|
|
"execution_count": 15,
|
|
"metadata": {},
|
|
"output_type": "execute_result"
|
|
}
|
|
],
|
|
"source": [
|
|
"ex1 = Animals()\n",
|
|
"ex1.reset()\n",
|
|
"ex1.factz([\n",
|
|
" Fact(color='red-brown'),\n",
|
|
" Fact(pattern='dark stripes'),\n",
|
|
" Fact('sharp teeth'),\n",
|
|
" Fact('claws'),\n",
|
|
" Fact('forward looking eyes'),\n",
|
|
" Fact('gives milk')])\n",
|
|
"ex1.run()\n",
|
|
"ex1.facts"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": null,
|
|
"metadata": {},
|
|
"outputs": [],
|
|
"source": []
|
|
},
|
|
{
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"cell_type": "markdown",
|
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"metadata": {},
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"source": [
|
|
"---\n\n<!-- CO-OP TRANSLATOR DISCLAIMER START -->\n**Disclaimer**: \nDit document is vertaald met behulp van de AI-vertalingsdienst [Co-op Translator](https://github.com/Azure/co-op-translator). Hoewel we streven naar nauwkeurigheid, kan deze automatische vertaling fouten of onnauwkeurigheden bevatten. Het originele document in de oorspronkelijke taal moet als gezaghebbende bron worden beschouwd. Voor cruciale informatie wordt een professionele menselijke vertaling aanbevolen. Wij zijn niet aansprakelijk voor misverstanden of verkeerde interpretaties die voortvloeien uit het gebruik van deze vertaling.\n<!-- CO-OP TRANSLATOR DISCLAIMER END -->\n"
|
|
]
|
|
}
|
|
],
|
|
"metadata": {
|
|
"kernelspec": {
|
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"display_name": "Python 3.7.4 64-bit (conda)",
|
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"metadata": {
|
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"interpreter": {
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"hash": "86193a1ab0ba47eac1c69c1756090baa3b420b3eea7d4aafab8b85f8b312f0c5"
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}
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},
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
|
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.11.2"
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},
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"coopTranslator": {
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"original_hash": "8ef43db4b9182239fd150a76bd494fdb",
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"translation_date": "2026-01-16T02:52:22+00:00",
|
|
"source_file": "lessons/2-Symbolic/Animals.ipynb",
|
|
"language_code": "nl"
|
|
}
|
|
},
|
|
"nbformat": 4,
|
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"nbformat_minor": 2
|
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} |