elephants.ipynb

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   "source": [
    "# Elephants as prototypes"
   ]
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   "source": [
    "This is a simple example illustrating the concept of _prototypes_ using elephants. A similar example is often found in knowledge representation discussions.\n",
    "\n",
    "This notebook is currently running using:"
   ]
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     "data": {
      "text/plain": [
       "\u001b[1mtrue"
      ]
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   "source": [
    "%versions"
   ]
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    "Prototypes are neither instances or classes but either standalone objects as `clyde`, our prototypical but concrete elephant:"
   ]
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       "\u001b[1mtrue"
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   "source": [
    "%%file clyde.lgt\n",
    "\n",
    ":- object(clyde).\n",
    "\n",
    "\t:- public(color/1).\n",
    "\tcolor(grey).\n",
    "\n",
    "\t:- public(number_of_legs/1).\n",
    "\tnumber_of_legs(4).\n",
    "\n",
    ":- end_object."
   ]
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      "text/plain": [
       "\u001b[1mN = 4"
      ]
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   ],
   "source": [
    "clyde::number_of_legs(N)."
   ]
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       "\u001b[1mC = grey"
      ]
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   "source": [
    "clyde::color(C)."
   ]
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   "source": [
    "Or objects that are derived from other prototypes as `fred`, which is like `clyde` except in his color:"
   ]
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   "outputs": [
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     "data": {
      "text/plain": [
       "\u001b[1mtrue"
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   "source": [
    "%%file fred.lgt\n",
    "\n",
    ":- object(fred,\n",
    "\textends(clyde)).\n",
    "\n",
    "\t% override inherited definition\n",
    "\tcolor(white).\n",
    "\n",
    ":- end_object."
   ]
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       "\u001b[1mN = 4"
      ]
     },
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   "source": [
    "fred::number_of_legs(N)."
   ]
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       "\u001b[1mC = white"
      ]
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   ],
   "source": [
    "fred::color(C)."
   ]
  }
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