In the following exercises, assess whether the indicated sentence is a logical truth in the blocks language.
If so, use Fitch to construct a formal proof of the sentence from no premises (using Ana Con if
necessary, but only applied to literals). If not, use Tarski's World to construct a counterexample. (A
counterexample here will simply be a world that makes the purported conclusion false.)
6.34
6.35
$\neg(a = b \land Dodec(a) \land \neg Dodec(b))$
$\neg(a = b \land Dodec(a) \land Cube(b))$
6.36
6.37
$\neg(a = b \land b = c \land a \ne c)$
$\neg(a \ne b \land b \ne c \land a = c)$
6.38
$\neg(SameRow(a, b) \land SameRow(b, c) \land FrontOf(c, a))$
6.39
$\neg(SameCol(a, b) \land SameCol(b, c) \land FrontOf(a, c))$
