minor details in logic folder

Author: fchapoton

src/sage/logic/booleval.py

@@ -23,15 +23,15 @@
     sage: booleval.eval_formula(t, d)
     False
 """
-#*****************************************************************************
+# ****************************************************************************
 #       Copyright (C) 2006 Chris Gorecki <[email protected]>
 #       Copyright (C) 2013 Paul Scurek <[email protected]>
 #
 #  Distributed under the terms of the GNU General Public License (GPL)
 #  as published by the Free Software Foundation; either version 2 of
 #  the License, or (at your option) any later version.
-#                  http://www.gnu.org/licenses/
-#*****************************************************************************
+#                  https://www.gnu.org/licenses/
+# ****************************************************************************
 
 from . import logicparser
 
@@ -72,8 +72,8 @@ def eval_formula(tree, vdict):
     """
     global __vars
     __vars = vdict
-    b = logicparser.apply_func(tree, eval_f)
-    return b
+    return logicparser.apply_func(tree, eval_f)
+
 
 def eval_f(tree):
     r"""
@@ -104,6 +104,7 @@ def eval_f(tree):
     """
     return eval_op(tree[0], tree[1], tree[2])
 
+
 def eval_op(op, lv, rv):
     r"""
     Evaluate ``lv`` and ``rv`` according to the operator ``op``.

src/sage/logic/boolformula.py

@@ -148,7 +148,7 @@
                    ('->', '\\rightarrow ')]
 
 
-class BooleanFormula():
+class BooleanFormula:
     """
     Boolean formulas.
 
@@ -673,10 +673,7 @@ def is_satisfiable(self):
             False
         """
         table = self.truthtable().get_table_list()
-        for row in table[1:]:
-            if row[-1] is True:
-                return True
-        return False
+        return any(row[-1] is True for row in table[1:])
 
     def is_tautology(self):
         r"""
@@ -1309,11 +1306,11 @@ def reduce_op(self, tree):
         if tree[0] == '<->':
             # parse tree for (~tree[1]|tree[2])&(~tree[2]|tree[1])
             new_tree = ['&', ['|', ['~', tree[1], None], tree[2]],
-                       ['|', ['~', tree[2], None], tree[1]]]
+                        ['|', ['~', tree[2], None], tree[1]]]
         elif tree[0] == '^':
             # parse tree for (tree[1]|tree[2])&~(tree[1]&tree[2])
             new_tree = ['&', ['|', tree[1], tree[2]],
-                       ['~', ['&', tree[1], tree[2]], None]]
+                        ['~', ['&', tree[1], tree[2]], None]]
         elif tree[0] == '->':
             # parse tree for ~tree[1]|tree[2]
             new_tree = ['|', ['~', tree[1], None], tree[2]]
@@ -1354,10 +1351,7 @@ def dist_not(self, tree):
         if tree[0] == '~' and isinstance(tree[1], list):
             op = tree[1][0]
             if op != '~':
-                if op == '&':
-                    op = '|'
-                else:
-                    op = '&'
+                op = '|' if op == '&' else '&'
                 new_tree = [op, ['~', tree[1][1], None], ['~', tree[1][2], None]]
                 return logicparser.apply_func(new_tree, self.dist_not)
             else:

src/sage/logic/logic.py

@@ -15,16 +15,16 @@
 
 - Paul Scurek (2013-08-03): updated docstring formatting
 """
-#*****************************************************************************
+# ****************************************************************************
 #       Copyright (C) 2007 Chris Gorecki <[email protected]>
 #       Copyright (C) 2007 William Stein <[email protected]>
 #       Copyright (C) 2013 Paul Scurek <[email protected]>
 #
 #  Distributed under the terms of the GNU General Public License (GPL)
 #  as published by the Free Software Foundation; either version 2 of
 #  the License, or (at your option) any later version.
-#                  http://www.gnu.org/licenses/
-#*****************************************************************************
+#                  https://www.gnu.org/licenses/
+# ****************************************************************************
 
 import string
 
@@ -36,6 +36,7 @@
 vars = {}
 vars_order = []
 
+
 class SymbolicLogic:
     """
     EXAMPLES:
@@ -184,7 +185,7 @@ def truthtable(self, statement, start=0, end=-1):
             end = 2 ** len(vars)
         table = [statement]
         keys = vars_order
-        for i in range(start,end):
+        for i in range(start, end):
             j = 0
             row = []
             for key in reversed(keys):
@@ -270,10 +271,7 @@ def print_table(self, table):
             line = s = ""
             i = 0
             for e in row:
-                if e == 'True':
-                    j = 2
-                else:
-                    j = 1
+                j = 2 if e == 'True' else 1
                 s = e + ' ' * j
                 if i < len(vars_len):
                     while len(s) <= vars_len[i]:
@@ -370,6 +368,7 @@ def prove(self, statement):
         """
         raise NotImplementedError
 
+
 def get_bit(x, c):
     r"""
     Determine if bit ``c`` of the number ``x`` is 1.
@@ -402,10 +401,7 @@ def get_bit(x, c):
     """
     bits = []
     while x > 0:
-        if x % 2 == 0:
-            b = 'False'
-        else:
-            b = 'True'
+        b = 'False' if x % 2 == 0 else 'True'
         x = x // 2
         bits.append(b)
     if c > len(bits) - 1:
@@ -456,6 +452,7 @@ def eval(toks):
         raise RuntimeError
     return stack[0]
 
+
 def eval_ltor_toks(lrtoks):
     r"""
     Evaluates the expression contained in ``lrtoks``.
@@ -494,6 +491,7 @@ def eval_ltor_toks(lrtoks):
         raise RuntimeError
     return lrtoks[0]
 
+
 def reduce_bins(lrtoks):
     r"""
     Evaluate ``lrtoks`` to a single boolean value.
@@ -531,6 +529,7 @@ def reduce_bins(lrtoks):
             reduce_bins(lrtoks)
         i += 1
 
+
 def reduce_monos(lrtoks):
     r"""
     Replace monotonic operator/variable pairs with a boolean value.
@@ -566,6 +565,7 @@ def reduce_monos(lrtoks):
             del lrtoks[i + 1]
         i += 1
 
+
 def eval_mon_op(args):
     r"""
     Return a boolean value based on the truth table of the operator
@@ -592,21 +592,17 @@ def eval_mon_op(args):
 
         sage: log = SymbolicLogic()
         sage: s = log.statement("!(a&b)|!a"); s
-        [['OPAREN', 'NOT', 'OPAREN', 'a', 'AND', 'b', 'CPAREN', 'OR', 'NOT', 'a', 'CPAREN'],
+        [['OPAREN', 'NOT', 'OPAREN', 'a', 'AND', 'b', 'CPAREN', 'OR',
+         'NOT', 'a', 'CPAREN'],
          {'a': 'False', 'b': 'False'},
          ['a', 'b']]
         sage: sage.logic.logic.eval_mon_op(['NOT', 'a'])
         'True'
     """
-    if args[1] != 'True' and args[1] != 'False':
-        val = vars[args[1]]
-    else:
-        val = args[1]
+    val = vars[args[1]] if args[1] != 'True' and args[1] != 'False' else args[1]
+
+    return 'False' if val == 'True' else 'True'
 
-    if val == 'True':
-        return 'False'
-    else:
-        return 'True'
 
 def eval_bin_op(args):
     r"""
@@ -660,6 +656,7 @@ def eval_bin_op(args):
     elif args[1] == 'IFF':
         return eval_iff_op(lval, rval)
 
+
 def eval_and_op(lval, rval):
     r"""
     Apply the 'and' operator to ``lval`` and ``rval``.
@@ -691,14 +688,8 @@ def eval_and_op(lval, rval):
         sage: sage.logic.logic.eval_and_op('True', 'True')
         'True'
     """
-    if lval == 'False' and rval == 'False':
-        return 'False'
-    elif lval == 'False' and rval == 'True':
-        return 'False'
-    elif lval == 'True' and rval == 'False':
-        return 'False'
-    elif lval == 'True' and rval == 'True':
-        return 'True'
+    return 'True' if (lval == 'True' == rval) else 'False'
+
 
 def eval_or_op(lval, rval):
     r"""
@@ -731,14 +722,8 @@ def eval_or_op(lval, rval):
         sage: sage.logic.logic.eval_or_op('True', 'True')
         'True'
     """
-    if lval == 'False' and rval == 'False':
-        return 'False'
-    elif lval == 'False' and rval == 'True':
-        return 'True'
-    elif lval == 'True' and rval == 'False':
-        return 'True'
-    elif lval == 'True' and rval == 'True':
-        return 'True'
+    return 'True' if (lval == 'True' or rval == 'True') else 'False'
+
 
 def eval_ifthen_op(lval, rval):
     r"""
@@ -772,14 +757,8 @@ def eval_ifthen_op(lval, rval):
         sage: sage.logic.logic.eval_ifthen_op('True', 'True')
         'True'
     """
-    if lval == 'False' and rval == 'False':
-        return 'True'
-    elif lval == 'False' and rval == 'True':
-        return 'True'
-    elif lval == 'True' and rval == 'False':
-        return 'False'
-    elif lval == 'True' and rval == 'True':
-        return 'True'
+    return 'False' if (lval == 'True' and rval == 'False') else 'True'
+
 
 def eval_iff_op(lval, rval):
     r"""
@@ -813,14 +792,8 @@ def eval_iff_op(lval, rval):
         sage: sage.logic.logic.eval_iff_op('True', 'True')
         'True'
     """
-    if lval == 'False' and rval == 'False':
-        return 'True'
-    elif lval == 'False' and rval == 'True':
-        return 'False'
-    elif lval == 'True' and rval == 'False':
-        return 'False'
-    elif lval == 'True' and rval == 'True':
-        return 'True'
+    return 'True' if (lval == rval) else 'False'
+
 
 def tokenize(s, toks):
     r"""
@@ -887,7 +860,8 @@ def tokenize(s, toks):
                 if tok[0] not in string.ascii_letters:
                     valid = 0
                 for c in tok:
-                    if c not in string.ascii_letters and c not in string.digits and c != '_':
+                    if not (c in string.ascii_letters
+                            or c in string.digits or c == '_'):
                         valid = 0
 
             if valid == 1:

src/sage/logic/logicparser.py

@@ -75,15 +75,15 @@
     sage: logicparser.tree_parse(r, polish = True)
     ['|', ['~', ['~', 'a']], 'b']
 """
-#*****************************************************************************
+# ****************************************************************************
 #       Copyright (C) 2007 Chris Gorecki <[email protected]>
 #       Copyright (C) 2013 Paul Scurek <[email protected]>
 #
 #  Distributed under the terms of the GNU General Public License (GPL)
 #  as published by the Free Software Foundation; either version 2 of
 #  the License, or (at your option) any later version.
 #                  https://www.gnu.org/licenses/
-#*****************************************************************************
+# ****************************************************************************
 
 import string
 
@@ -164,6 +164,7 @@ def polish_parse(s):
         return vars_order
     return tree
 
+
 def get_trees(*statements):
     r"""
     Return the full syntax parse trees of the statements.
@@ -276,6 +277,7 @@ def recover_formula(prefix_tree):
         return formula
     return formula[1:-1]
 
+
 def recover_formula_internal(prefix_tree):
     r"""
     Recover the formula from a parse tree in prefix form.
@@ -385,6 +387,7 @@ def prefix_to_infix(prefix_tree):
         raise TypeError("the input must be a parse tree as a list")
     return apply_func(prefix_tree, to_infix_internal)
 
+
 def to_infix_internal(prefix_tree):
     r"""
     Convert a simple parse tree from prefix form to infix form.
@@ -434,6 +437,7 @@ def to_infix_internal(prefix_tree):
         return [prefix_tree[1], prefix_tree[0], prefix_tree[2]]
     return prefix_tree
 
+
 def tokenize(s):
     r"""
     Return the tokens and the distinct variables appearing in a boolean
@@ -516,6 +520,7 @@ def tokenize(s):
     toks.append(')')
     return toks, vars_order
 
+
 def tree_parse(toks, polish=False):
     r"""
     Return a parse tree from the tokens in ``toks``.
@@ -572,6 +577,7 @@ def tree_parse(toks, polish=False):
             stack.append(branch)
     return stack[0]
 
+
 def parse_ltor(toks, n=0, polish=False):
     r"""
     Return a parse tree from ``toks``, where each token in ``toks`` is atomic.
@@ -657,6 +663,7 @@ def parse_ltor(toks, n=0, polish=False):
         raise SyntaxError
     return toks[0]
 
+
 def apply_func(tree, func):
     r"""
     Apply ``func`` to each node of ``tree``, and return a new parse tree.