Projective description and properties of the G-orbits of (2x3x3)- tensors.

(from [Lavrauw-Sheekey 2015])




Description and RepresentativeTensor Rank
Rank Distr.



o1 e1 e1 e1 1
PG(A1) : Point on S3,3 [1,0,0]
PG(A2) : Point on S2,3 [1,0,0]
PG(A3) : Point on S2,3 [1,0,0]



o2 e1 (e1 e1 + e2 e2) 2
PG(A1) : Point of rank 2 [0,1,0]
PG(A2) : Line on S2,3 [q + 1,0,0]
PG(A3) : Line on S2,3 [q + 1,0,0]



o3 e1 (e1 e1 + e2 e2 + e3 e3) 3
PG(A1) : Point of rank 3 [0,0,1]
PG(A2) : Plane on S2,3 [q2 + q + 1,0,0]
PG(A3) : Plane on S2,3 [q2 + q + 1,0,0]



o4 e1 e1 e1 + e2 e1 e2 2
PG(A1) : Line on S3,3 [q + 1,0,0]
PG(A2) : Point of rank 2 [0,1,0]
PG(A3) : Line on S2,3 [q + 1,0,0]



o5 e1 e1 e1 + e2 e2 e2 2
PG(A1) : Secant line [2,q - 1,0]
PG(A2) : Secant line [2,q - 1,0]
PG(A3) : Secant line [2,q - 1,0]



o6 e1 e1 e1 + e2 (e1 e2 + e2 e1) 3
PG(A1) : Tangent line contained in an < S2,2 > [1,q,0]
PG(A2) : Tangent line contained in an < S2,2 > [1,q,0]
PG(A3) : Tangent line contained in an < S2,2 > [1,q,0]



o7 e1 e1 e3 + e2 (e1 e1 + e2 e2) 3
PG(A1) : Tangent line contained in an < S2,3 >, [1,q,0]
not contained in an < S2,2 >
PG(A2) : Tangent line, not contained in an < S2,2 > [1,q,0]
PG(A3) : Plane containing 2 lines of an S2,2 [2q + 1,q2 - q,0]



o8 e1 e1 e1 + e2 (e2 e2 + e3 e3) 3
PG(A1) : Tangent line not contained in an < S2,3 >, [1,1,q - 1]
containing a point of rank 2
PG(A2) : Plane containing a line and a point of S2,3 [q + 2,q2 - 1,0]
not contained in an < S2,2 >
PG(A3) : Plane containing a line and a point of S2,3 [q + 2,q2 - 1,0]
not contained in an < S2,2 >



o9 e1 e3 e1 + e2 (e1 e1 + e2 e2 + e3 e3) 4
PG(A1) : Tangent line not contained in an < S2,3 >, [1,0,q]
not containing a point of rank 2
PG(A2) : Plane containing a line of S2,3, [q + 1,q2,0]
not contained in an < S2,2 >
PG(A3) : Plane containing a line of S2,3 not contained in an < S2,2 > [q + 1,q2,0]



o10 e1 (e1 e1 + e2 e2 + ue1 e2) + e2 (e1 e2 + ve2 e1) 3
2 + uvλ - 10 for all λ Fq
PG(A1) : Line of constant rank 2, contained in an < S2,2 >, [0,q + 1,0]
PG(A2) : Line of constant rank 2, contained in an < S2,2 >, [0,q + 1,0]
PG(A3) : Line of constant rank 2, contained in an < S2,2 >, [0,q + 1,0]



o11 e1 (e1 e1 + e2 e2) + e2 (e1 e2 + ve2 e3) 3
PG(A1) : Line of constant rank 2, contained in an < S2,3 >, [0,q + 1,0]
but not in an < S2,2 >
PG(A2) : Line of constant rank 2, contained in an < S2,3 >, [0,q + 1,0]
but not in an < S2,2 >
PG(A3) : Plane in an < S2,2 >, meeting in a conic [q + 1,q2,0]



o12 e1 (e1 e1 + e2 e2) + e2 (e1 e3 + e3 e2) 4
PG(A1) : Line of constant rank 2, not contained in an < S2,3 >, [0,q + 1,0]
PG(A2) : Plane containing a line of S2,3 [q + 1,q2,0]
PG(A3) : Plane containing a line of S2,3 [q + 1,q2,0]



o13 e1 (e1 e1 + e2 e2) + e2 (e1 e2 + e3 e3) 4
PG(A1) : Line with 2 points of rank 2 [0,2,q - 1]
PG(A2) : Plane containing 2 points of S2,3 [2,q2 + q - 1,0]
PG(A3) : Plane containing 2 points of S2,3 [2,q2 + q - 1,0]



o14 e1 (e1 e1 + e2 e2) + e2 (e2 e2 + e3 e3) 3
PG(A1) : Line with 3 points of rank 2 [0,2,q - 1]
PG(A2) : Plane contain ing 3 points of S2,3 [0,3,q - 2]
PG(A3) : Plane containing 3 points of S2,3 [0,3,q - 2]



o15 e1 (e + ue1 e2) + e2 (e1 e2 + ve2 e1); 4
2 + uvλ - 10 for all λ Fq
and e = e1 e1 + e2 e2 + e3 e3.
PG(A1) : Line having one point of rank 2 [0,1,q]
PG(A2) : Plane containing one point of S2,3 [1,q2 + q,0]
PG(A3) : Plane containing one point of S2,3 [1,q2 + q,0]



o16 e1 (e1 e1 + e2 e2 + e3 e3) + e2 (e1 e2 + e2 e3) 4
PG(A1) : Line having one point of rank 2 [0,1,q]
PG(A2) : Plane containing one point of S2,3 [1,q2 + q,0]
PG(A3) : Plane containing one point of S2,3 [1,q2 + q,0]



o17 e1 (e) + e2 (e1 e2 + e2 e3 + e3 (αe1 + βe2 + γe3)); 4 if q 3
λ3 + γλ2 - βλ + α0 for all λ Fq 5 if q = 2
and e = e1 e1 + e2 e2 + e3 e3.
PG(A1) :Line of constant rank 3 [0,0,q + 1]
PG(A2) :Plane disjoint from S2,3 [0,q2 + q + 1,0]
PG(A3) :Plane disjoint from S2,3 [0,q2 + q + 1,0]