Universe = Domain: a, b, c, d Knows(a,a) Knows(b,b) Knows(c,c) Knows(d,d) Knows(a,b) Knows(b,c) Knows(a,d)
x -> a, y-> d, z->b For_All(x) Knows(x,x) AND Exists(y)not Knows(z,y)
Let universe U = {"PersonA", "PersonB", "PersonC", "PersonD"} Knows := {("PersonA", "PersonA"), ("PersonB", "PersonB"), ("PersonC", "PersonC"}, ("PersonD","PersonD")} F := (∀x)Knows(x,x)∧(∃y)¬Knows(z,y)[z -> "PersonB"] T ¬Knows(z,y)[z -> "PersonB", y -> "PersonA"] F T(Edited: 2022-11-02)
(∀x)Knows(x,x) ∧ (∃y)¬Knows(z,y) Domain: (Alice, Bob, Cali) Knows: (Alice, Alice), (Bob, Bob), (Cali, Cali) Right side evaluates to true if we set it's variables to (Bob, Alice) or (Alice, Bob) or (Bob, Cali) or (Alice, Cali) or (Cali, Bob) or (Cali, Alice)
Predicate: Knows(X, Y)
Model: M = {“Alice”, “Bob”, “Dave”} Knows(“Alice”, “Alice”) Knows(“Bob”, “Bob”) Knows(“Dave”, “Dave”)
Formula: (∀x)Knows(x,x)∧(∃y)¬Knows(z,y)
Variable Assignment: x -> “Dave”, Y -> “Alice”, Z -> “Bob”(Edited: 2022-11-02)
(∀x)Knows(x,x) ∧ (∃y)¬Knows(z,y) Universe = ["John", "Peter", "Bob"] (∀x)Knows(x,x) := {["John", "John"], ["Peter", "Peter"], ["Bob", "Bob"]} = T (∃y)¬Knows(z,y) := [z = "John", y = "Peter"] = T (∀x)Knows(x,x) ∧ (∃y)¬Knows(z,y) = T