 PROPOSITIONAL
CALCULUS
 PREDICATE
CALCULUS
 Designed for representing discourse of mathematics.
 Both are simple CFG.
 Strings in both are known as Formulas
SYNTAX OF PROPOSITIONAL CALCULUS
Strings are known as Formulas.
A formula is constructed with the aid of Logical Connectives such
as AND,OR, NOT denoted by the symbols ^,v,¬
• The word blueberry has
two consecutive r’s
OR
• The word peach has six
letters
 A : the word blueberry
has two consecutive r’s
 B :the word peach has
six letter
(A V B)
 A : Stands for the word
“ watermelon has nine
letters,”
 B : Stands for the word
“ blueberry has two
consecutive r’s , “
 C : Stands for the word
“peach has six letters “
 (A ^(B v ¬C)
 “ Either Jim or John is
here , but not both “
 Jim is here or John is here
AND
 John is not here or Jim is
not here
((A V B) ^ (¬A V ¬B))
 Jim is here or John is
here;
AND
 It is not the case that Jim
is here AND John is here
((A V B) ^ ¬ (A ^ B))
DEFINITION
 The formulas of the propositinal calculus are the
strings generated by the following CFG
G = (V,∑,R,S)
V = ∑ U {S,N}
∑ = { A,I,S,V,^,¬(,)}
R = { N ->e
N ->NI
S ->AN$
S ->(S V S)
S ->(S ^ S)
S -> ¬S }
If F and G are any two formula
o ( F ^ G ) :- Conjunction of F and G
o ( F v G ) :- Disjunction of F and G
o ¬ F :- Negation of F
o ( F -> G) :- If F then G
( F -> G) = ( ¬F V G )
(F <-> G) = ( (F->G) ^ (G -> F) )
A B (A V B)
T T T
T F T
F T T
F F F
DISJUNCTIONCONJUNCTION
A B (A ˄ B)
T T T
T F F
F T F
F F F
NOT
A ¬ A
T F
F T
CONDITIONAL
A ¬ A B
(A -> B)
=(¬A V B)
T F T T
T F F F
F T T T
F T F T
VALIDITY & SATISFIABILITY
VALIDITY
 F is valid , if every truth
assignment appropriate to
F verifies.
 i.e , F is a Tautology
SATISFIABILITY &
UNSATISFIABILITY
 SATISFIABLE :- If the truth
table for the formulas
contains atleast one T’s.
 UNSATISFIABLE :- If the
truth table for the formulas
contains all False.
“ EVERY VALID FORMULA IS SATISFIABLE. BUT EVERY
SATISFIABLE FORMULA IS NOT VALID ”
THANK YOU

The propositional calculus

  • 2.
     PROPOSITIONAL CALCULUS  PREDICATE CALCULUS Designed for representing discourse of mathematics.  Both are simple CFG.  Strings in both are known as Formulas
  • 3.
    SYNTAX OF PROPOSITIONALCALCULUS Strings are known as Formulas. A formula is constructed with the aid of Logical Connectives such as AND,OR, NOT denoted by the symbols ^,v,¬
  • 4.
    • The wordblueberry has two consecutive r’s OR • The word peach has six letters  A : the word blueberry has two consecutive r’s  B :the word peach has six letter (A V B)
  • 5.
     A :Stands for the word “ watermelon has nine letters,”  B : Stands for the word “ blueberry has two consecutive r’s , “  C : Stands for the word “peach has six letters “  (A ^(B v ¬C)
  • 6.
     “ EitherJim or John is here , but not both “  Jim is here or John is here AND  John is not here or Jim is not here ((A V B) ^ (¬A V ¬B))  Jim is here or John is here; AND  It is not the case that Jim is here AND John is here ((A V B) ^ ¬ (A ^ B))
  • 7.
    DEFINITION  The formulasof the propositinal calculus are the strings generated by the following CFG G = (V,∑,R,S) V = ∑ U {S,N} ∑ = { A,I,S,V,^,¬(,)} R = { N ->e N ->NI S ->AN$ S ->(S V S) S ->(S ^ S) S -> ¬S }
  • 8.
    If F andG are any two formula o ( F ^ G ) :- Conjunction of F and G o ( F v G ) :- Disjunction of F and G o ¬ F :- Negation of F o ( F -> G) :- If F then G ( F -> G) = ( ¬F V G ) (F <-> G) = ( (F->G) ^ (G -> F) )
  • 9.
    A B (AV B) T T T T F T F T T F F F DISJUNCTIONCONJUNCTION A B (A ˄ B) T T T T F F F T F F F F
  • 10.
    NOT A ¬ A TF F T CONDITIONAL A ¬ A B (A -> B) =(¬A V B) T F T T T F F F F T T T F T F T
  • 11.
    VALIDITY & SATISFIABILITY VALIDITY F is valid , if every truth assignment appropriate to F verifies.  i.e , F is a Tautology SATISFIABILITY & UNSATISFIABILITY  SATISFIABLE :- If the truth table for the formulas contains atleast one T’s.  UNSATISFIABLE :- If the truth table for the formulas contains all False. “ EVERY VALID FORMULA IS SATISFIABLE. BUT EVERY SATISFIABLE FORMULA IS NOT VALID ”
  • 12.

Editor's Notes

  • #11 H.W : FIND THE TRUTH TABLE FOR (A <-> B)