  It is known that any finite idempotent algebra that satisfies a nontrivial
Maltsev condition must satisfy the linear one-equality Maltsev condition (a
variant of the term discovered by M. Siggers and refined by K. Kearnes, P.
Markovi\'c, and R. McKenzie):
  \[
  t(r,a,r,e)\approx t(a,r,e,a).
  \] We show that if we drop the finiteness assumption, the $k$-ary weak near
unanimity equations imply only trivial linear one-equality Maltsev conditions
for every $k\geq 3$. From this it follows that there is no nontrivial linear
one-equality condition that would hold in all idempotent algebras having Taylor
terms.
  Miroslav Ol\v{s}\'ak has recently shown that there is a weakest nontrivial
strong Maltsev condition for idempotent algebras. Ol\v{s}\'ak has found several
such (mutually equivalent) conditions consisting of two or more equations. Our
result shows that Ol\v{s}\'ak's equation systems can't be compressed into just
one equation.
