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• ����– UD�2�3�4�
��1�logically speaking
• ������logically speaking��–���statement statement form�����– statement form��������–������������
%&1�logically speaking ( )
• ��"$�statement form������#��������– negation����– disjunction����– conjunction����– implication�!��– equivalence���
– tautology�����– contradiction�� ��
��2�truth table
• ������statement form���� �������������
��2�truth table (�)
• �������������plan ���– If it is Wednesday, then Mr. French eats only pickles.– If it is Monday, then Mr. French eats only chocolate.– Mr. French is eating chocolate.– ����� ����
��2�truth table (�)
• �����������������– Mr. Hamburger is German or Swiss.– Mr. Hamburger is not Swiss.–���Mr. Hamburger�� ��
��2�truth table (�)
• �����������������– Mr. Hamburger is German or Swiss.– Mr. Hamburger is not Swiss.–���Mr. Hamburger�� ��
G S G∨S ¬ST T T FT F T TF T T FF F F T
��2�truth table ( )
• �����������������– Knights and Knaves• John: We are both knaves.• Bill: …
��2�truth table ( )
• �����������������– Knights and Knaves• John: We are both knaves.• Bill: …
J B ¬J∧¬B J↔(¬J∧¬B)T T F FT F F FF T F TF F T F
��2�truth table ( )
• �����������������– Knights and Knaves• John: We are the same kind.• Bill: We are of different kinds.
��2�truth table ( )
• �����������������– Knights and Knaves• John: We are the same kind.• Bill: We are of different kinds.
J B (J↔(J↔B))∧(B↔¬(J↔B))T T FT F FF T TF F F
��3�equivalent statement forms
• ���equivalent statement forms�• ��������equivalence���� �• �����������
#$3�equivalent statement forms (�)
• � � �����!�����statement form����equivalent statement form�– A∨B– A∧B
• ����"�������
#$3�equivalent statement forms (�)
• � � �����!�����statement form����equivalent statement form�– A∨B�¬A→B– A∧B�¬(A→¬B)
• ����"�������
��3�equivalent statement forms (�)
• ��������������statement form� ��equivalent statement form�– ¬A– A∧B– A∨B
��3�equivalent statement forms (�)
• �������������statement form���equivalent statement form�– ¬A– A∧B– A∨B
��3�equivalent statement forms (�)
• �������������statement form���equivalent statement form�– ¬A– A∧B– A∨B
��3�equivalent statement forms (�)
• ����� ��equivalent statement forms����������
��3�equivalent statement forms (�)
• �������������������� ��paraphrase����– Knights and Knaves• John: We are both knaves.• Bill: …
J B ¬J∧¬B J↔(¬J∧¬B)T T F FT F F FF T F TF F T F
(J∧(¬J∧¬B))∨(¬J∧¬(¬J∧¬B))= (J∧¬J∧¬B)∨(¬J∧(¬¬J∨¬¬B))=F∨(¬J∧(J∨B))=¬J∧(J∨B)=(¬J∧J)∨(¬J∧B)=F∨(¬J∧B)=¬J∧B
��3�equivalent statement forms (�)
(J∧(¬J∧¬B))∨(¬J∧¬(¬J∧¬B))= (J∧¬J∧¬B)∨(¬J∧(¬¬J∨¬¬B))=F∨(¬J∧(J∨B))=¬J∧(J∨B)=(¬J∧J)∨(¬J∧B)=F∨(¬J∧B)=¬J∧B���������� ������
��3�equivalent statement forms (�)
��4�set notation and quantifiers
• ������• ������� ��������– extensional definition• {-1, 1}• {1}
– intensional definition• {2n : n∈Z}• {(m,n)∈R2 : y=0}
��4�set notation and quantifiers ()
• ������� ��
• �������������– For all x∈A, property p(x) holds.– For some x∈A, property p(x) holds.
��4�set notation and quantifiers ()
• �������������– For all x∈A, property p(x) holds.– For some x∈A, property p(x) holds.
( )( )xpAxx ®Î" ,( )( )xpAxx ÙÎ$ ,
��4�set notation and quantifiers ()
• ���� ��������– For all x∈A, property p(x) holds.– For some x∈A, property p(x) holds.
• �������� �
( )( )xpAxx ®Î" ,( )( )xpAxx ÙÎ$ ,
( )( )xpAxx ®Î$ ,
��4�set notation and quantifiers (�)
• ������������
• ���� �
��4�set notation and quantifiers (�)