## FANDOM

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The regressive product (usually referred to as the "meet") is the dual of the exterior product (or "join" in this context)

The dual specification of elements permits, for blades $A$ and $B$, the intersection (or meet) where the duality is to be taken relative to the smallest grade blade containing both $A$ and $B$ (the join).

$C \vee D := ((CI^{-1}) \wedge (DI^{-1}))I$

with $I$ the unit pseudoscalar of the algebra. The regressive product, like the exterior product, is associative.