Regularising Natural Dualities
نویسنده
چکیده
Given an algebra M we may adjoin an isolated zero to form an algebra M∞ satisfying all identities u ≈ v true in M for which u and v contain the same variables. Drawing on the structure theory of P lonka sums, we show that if M is a finite, dualisable algebra which is strongly irregular, then M∞ is also dualisable. Turning the construction of M∞ upside-down for the two-element left-zero band, we exhibit a duality for quasi-regular left-normal bands.
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