We define a notion |= as follows: for a set of L-formulas and an L-formula, we say that |= if whenever A |= , for A a model of L, we have A |= . So the definition of |= is like the definition of |=, but using models in place of interpretations. (a) Show that if |= then |= . (b) Show that the converse does not hold. That is, give an example of a lan- guage L, a set of L-formulas and an L-formula , and show that |= while |=