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sav08:homework09 [2008/04/25 15:06] vkuncak |
sav08:homework09 [2015/04/21 17:30] (current) |
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Prove that the quantifier-free theory of term algebras is convex (See [[Calculus of Computation Textbook]], Section 10.3.1). That is, show that, if $C$ is a conjunction of literals of form $t=t'$ and $t\neq t'$ where $t,t'$ are terms in some language (containing variables), and if formula | Prove that the quantifier-free theory of term algebras is convex (See [[Calculus of Computation Textbook]], Section 10.3.1). That is, show that, if $C$ is a conjunction of literals of form $t=t'$ and $t\neq t'$ where $t,t'$ are terms in some language (containing variables), and if formula | ||

- | \[ | + | \begin{equation*} |

- | C \rightarrow \bigvee_{i=1} t_i=t'_i | + | C \rightarrow \bigvee_{i=1}^n t_i=t'_i |

- | \] | + | \end{equation*} |

is valid (holds for all values of variables) in the Herbrand interpretation (where elements are ground terms and $\alpha(f)(t_1,\ldots,t_n)=f(t_1,\ldots,t_n)$), then for some $i$ | is valid (holds for all values of variables) in the Herbrand interpretation (where elements are ground terms and $\alpha(f)(t_1,\ldots,t_n)=f(t_1,\ldots,t_n)$), then for some $i$ | ||

- | \[ | + | \begin{equation*} |

C \rightarrow t_i=t'_i | C \rightarrow t_i=t'_i | ||

- | \] | + | \end{equation*} |

holds for all values of variables in the Herbrand interpretation. | holds for all values of variables in the Herbrand interpretation. | ||

If you use in your solution any theorem about term algebras that we did not prove in the class, you need to prove the theorem as well. | If you use in your solution any theorem about term algebras that we did not prove in the class, you need to prove the theorem as well. | ||