  A classical lattice gas model with translation-invariant finite range
competing interactions, for which there does not exist an equivalent
translation-invariant finite range nonfrustrated potential, is constructed. The
construction uses the structure of nonperiodic ground state configurations of
the model. In fact, the model does not have any periodic ground state
configurations. However, its ground state - a translation-invariant probability
measure supported by ground state configurations - is unique.
