Merge remote-tracking branch 'origin/master'

# Conflicts: # planning.py
aimacode · sofmonk · Mar 17, 2017 · Mar 17, 2017 · Mar 17, 2017 · Mar 17, 2017
commit aad19c832d89115bb5fa8827227f657c2eeeb760
diff --git a/logic.ipynb b/logic.ipynb
@@ -22,7 +22,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": 11,
    "metadata": {
     "collapsed": true
    },
@@ -306,11 +306,11 @@
     "|--------------------------|----------------------|-------------------------|---|---|\n",
     "| Negation                 | &not; P      | `~P`                       | `~P` | `Expr('~', P)`\n",
     "| And                      | P &and; Q       | `P & Q`                     | `P & Q` | `Expr('&', P, Q)`\n",
-    "| Or                       | P &or; Q | `P`<tt> &#124; </tt>`Q`| `P`<tt> &#124; </tt>`Q` | `Expr('`&#124;`', P, Q)`\n",
+    "| Or                       | P &or; Q | `P`<tt> &#124; </tt>`Q`| `P`<tt> &#124; </tt>`Q` | `Expr('`&#124;`', P, Q)\n",
     "| Inequality (Xor)         | P &ne; Q     | `P ^ Q`                | `P ^ Q`  | `Expr('^', P, Q)`\n",
     "| Implication                  | P &rarr; Q    | `P` <tt>&#124;</tt>`'==>'`<tt>&#124;</tt> `Q`   | `P ==> Q` | `Expr('==>', P, Q)`\n",
     "| Reverse Implication      | Q &larr; P     | `Q` <tt>&#124;</tt>`'<=='`<tt>&#124;</tt> `P`  |`Q <== P` | `Expr('<==', Q, P)`\n",
-    "| Equivalence            | P &harr; Q   | `P` <tt>&#124;</tt>`'<=>'`<tt>&#124;</tt> `Q`   |`P <=> Q` | `Expr('<=>', P, Q)`\n",
+    "| Equivalence            | P &harr; Q   | `P` <tt>&#124;</tt>`'<=>'`<tt>&#124;</tt> `Q`   |`P ==> Q` | `Expr('==>', P, Q)`\n",
     "\n",
     "Here's an example of defining a sentence with an implication arrow:"
    ]
@@ -412,6 +412,7 @@
     "\n",
     "The class `PropKB` can be used to represent a knowledge base of propositional logic sentences.\n",
     "\n",
+    "\n",
     "We see that the class `KB` has four methods, apart from `__init__`. A point to note here: the `ask` method simply calls the `ask_generator` method. Thus, this one has already been implemented and what you'll have to actually implement when you create your own knowledge base class (if you want to, though I doubt you'll ever need to; just use the ones we've created for you), will be the `ask_generator` function and not the `ask` function itself.\n",
     "\n",
     "The class `PropKB` now.\n",
@@ -421,6 +422,321 @@
     "* `retract(self, sentence)` : This function removes all the clauses of the sentence given, from the knowledge base. Like the `tell` function, you don't have to pass clauses to remove them from the knowledge base; any sentence will do fine. The function will take care of converting that sentence to clauses and then remove those."
    ]
   },
+  {
+   "cell_type": "heading",
+   "metadata": {},
+   "level": 6,
+   "source": [
+    "The following gives an idea how the python code works in logic.py:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "KB = PropKB()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "creates an empty knowledge base"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "True"
+      ]
+     },
+     "execution_count": 14,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "KB.tell(A & C)\n",
+    "KB.ask(A) == KB.ask(C) == {}"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "adds sentence and checks if KB entails the query."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    ""
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "False"
+      ]
+     },
+     "execution_count": 15,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "KB.ask(E)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 42,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{}"
+      ]
+     },
+     "execution_count": 42,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "kb.tell(E)\n",
+    "kb.ask(E)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "False"
+      ]
+     },
+     "execution_count": 16,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "KB.retract(C)\n",
+    "KB.ask(C)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "removes all clauses of 'C' from the sentence."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The truth table enumeration algorithm from Figure 7.10 codes as follows:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def tt_entails(kb, alpha):\n",
+    "    \n",
+    "    assert not variables(alpha)\n",
+    "    return tt_check_all(kb, alpha, prop_symbols(kb & alpha), {})"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Example:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "True"
+      ]
+     },
+     "execution_count": 7,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "tt_entails(expr('P & Q'), expr('Q'))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 27,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "True"
+      ]
+     },
+     "execution_count": 27,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "tt_check_all(expr('P & Q'), expr('Q'), prop_symbols(expr('Q')), {})"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 25,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "{B: True, A: True}\n{Q: True}\n"
+     ]
+    }
+   ],
+   "source": [
+    "print (dpll_satisfiable(expr('A & B')))\n",
+    "print (dpll_satisfiable(expr('P | Q')))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 41,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "{x: 2}\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(unify(x, 2, {}))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 46,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{B: True, C: True, A: True}"
+      ]
+     },
+     "execution_count": 46,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "WalkSAT([A & B, A & C], 0.5, 100 )"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 47,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "['Left', 'Left']"
+      ]
+     },
+     "execution_count": 47,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "transition = {'A': {'Left': 'A', 'Right': 'B'},\n",
+    "              'B': {'Left': 'A', 'Right': 'C'},\n",
+    "              'C': {'Left': 'B', 'Right': 'C'}}\n",
+    "\n",
+    "SAT_plan('C', transition, 'A', 3)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 49,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "<generator object fol_bc_or at 0x7f8d8c5f6ba0>"
+      ]
+     },
+     "execution_count": 49,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "fol_bc_ask(expr('P & Q'), expr('Q'))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 52,
+   "metadata": {},
+   "outputs": [
+    {
+     "ename": "AttributeError",
+     "evalue": "'Expr' object has no attribute 'clauses'",
+     "traceback": [
+      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+      "\u001b[0;31mAttributeError\u001b[0m                            Traceback (most recent call last)",
+      "\u001b[0;32m<ipython-input-52-1f559a7b8f18>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mpl_fc_entails\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mexpr\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'P & Q'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mexpr\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'Q'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+      "\u001b[0;32m/home/ubuntu/PycharmProjects/GSOC_17/sofmonk/aima-python/logic.py\u001b[0m in \u001b[0;36mpl_fc_entails\u001b[0;34m(KB, q)\u001b[0m\n\u001b[1;32m    498\u001b[0m     \"\"\"\n\u001b[1;32m    499\u001b[0m     count = {c: len(conjuncts(c.args[0]))\n\u001b[0;32m--> 500\u001b[0;31m              \u001b[0;32mfor\u001b[0m \u001b[0mc\u001b[0m \u001b[0;32min\u001b[0m \u001b[0mKB\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mclauses\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m    501\u001b[0m              if c.op == '==>'}\n\u001b[1;32m    502\u001b[0m     \u001b[0minferred\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mdefaultdict\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mbool\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
+      "\u001b[0;31mAttributeError\u001b[0m: 'Expr' object has no attribute 'clauses'"
+     ],
+     "output_type": "error"
+    }
+   ],
+   "source": [
+    "pl_fc_entails(expr('P & Q'), expr('Q'))"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -701,16 +1017,16 @@
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 3
+    "version": 3.0
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.4.3"
+   "version": "3.5.1"
   }
  },
  "nbformat": 4,
  "nbformat_minor": 0
-}
+}