**Background** Let V denote the standard (2-dimensional) module for the Lie algebra sl_{2}(C), or equivalently for the universal envelope U = U(sl_{2}(C)). The Temperley-Lieb algebra TL_{d} is the algebra of intertwiners of the d-fold tensor power of V.

TL

_{d}= End_{U}(V⊗…⊗V)

Now, let the symmetric group, and hence its group algebra CS_{d}, act on the right of V⊗…⊗V by permuting tensor factors. According to Schur-Weyl duality, V⊗…⊗V is a (U,CS_{d})-bimodule, with the image of each algebra inside End_{C}(V⊗…⊗V) being the centralizer of the other.

In other words, TL_{d} is a quotient of CS_{d}. The kernel is easy to describe. First decompose the group algebra into its Wedderburn components, one matrix algebra for each irrep of S_{d}. These are in bijection with partitions of d, which we should picture as Young diagrams. The representation is faithful on any component indexed by a diagram with at most 2 rows and it annihilates all other components.

So far, I have deliberately avoided the description of the Temperley-Lieb algebra as a diagram algebra in the sense that Kauffman describes it. Here's the rub: by changing variables in S_{d} to u_{i} = s_{i} + 1, where s_{i} = (i i+1), the structure coefficients in TL_{d} are all integers so that one can define a ℤ-form TL_{d}(ℤ) by these formulas.

TL

_{d}= C ⊗ TL_{d}(ℤ)

As product of matrix algebras (as in the Wedderburn decomposition), TL_{d} has a ℤ-form, as well: namely, matrices of the same dimensions over ℤ. These two rings are very different, the latter being rather trivial from the point of view of knot theory. They only become isomorphic after a base change to C.

There is a super-analog of this whole story. Let U = U(gl_{1|1}(C)), let V be the standard (1|1)-dimensional module, and let the symmetric group act by signed permutations (when two odd vectors cross, a sign pops up). An analogous Schur-Weyl duality statement holds, and so, by analogy, I call the algebra of intertwiners the super-Temperley-Lieb algebra, or STL_{d}.

Over the complex numbers, STL_{d} is a product of matrix algebras corresponding to the irreps of S_{d} indexed by hook partitions. Young diagrams are confined to one row and one column (super-row!). In that sense, STL_{d} is understood. However, idempotents involved in projecting onto these Wedderburn components are nasty things that cannot be defined over ℤ

**Question 1:** Does STL_{d} have a ℤ-form that is compatible with the standard basis for CS_{d}?

**Question 2:** I am pessimistic about Q1; hence, the follow up: why not? I suspect that this has something to do with cellularity.

**Question 3:** I care about q-deformations of everything mentioned: U_{q} and the Hecke algebra, respectively. What about here? I am looking for a presentation of STL_{d,q} defined over ℤ[q,q^{-1}].

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