Expert: A group of researchers claims to have shown that for an antenna to work equally well at all frequencies, it must be symmetrical in shape and have what is known as a fractal structure. Yet the new antenna developed by these researchers, which satisfies both of these criteria, in fact works better at frequencies below 250 megahertz than at frequencies above 250 megahertz. Hence, their claim is incorrect. The reasoning in the expert's argument is flawed because the argument ['takes for granted that there are only two possible alternatives, either below or above 250 megahertz', 'fails to provide a definition of the technical term "fractal"', 'contradicts itself by denying in its conclusion the claim of scientific authorities that it relies on in its premises', 'interprets an assertion that certain conditions are necessary as asserting that those conditions are sufficient']