  We propose an extension of the Sugeno integral for negative numbers, in the
spirit of the symmetric extension of Choquet integral, also called \Sipos\
integral. Our framework is purely ordinal, since the Sugeno integral has its
interest when the underlying structure is ordinal. We begin by defining
negative numbers on a linearly ordered set, and we endow this new structure
with a suitable algebra, very close to the ring of real numbers. In a second
step, we introduce the M\"obius transform on this new structure. Lastly, we
define the symmetric Sugeno integral, and show its similarity with the
symmetric Choquet integral.
