Recursos de colección
Project Euclid (Hosted at Cornell University Library) (192.320 recursos)
Proceedings of the Centre for Mathematics and its Applications
Proceedings of the Centre for Mathematics and its Applications
Tingley, Peter
We consider two well known constructions of link invariants. One uses skein theory: you
resolve each crossing of the link as a linear combination of things that don’t cross, until you eventually get a
linear combination of links with no crossings, which you turn into a polynomial. The other uses quantum
groups: you construct a functor from a topological category to some category of representations in such
a way that (directed framed) links get sent to endomorphisms of the trivial representation, which are just
rational functions. Certain instances of these two constructions give rise to essentially the same invariants,
but when one carefully matches them there...
Tingley, Peter
We consider two well known constructions of link invariants. One uses skein theory: you
resolve each crossing of the link as a linear combination of things that don’t cross, until you eventually get a
linear combination of links with no crossings, which you turn into a polynomial. The other uses quantum
groups: you construct a functor from a topological category to some category of representations in such
a way that (directed framed) links get sent to endomorphisms of the trivial representation, which are just
rational functions. Certain instances of these two constructions give rise to essentially the same invariants,
but when one carefully matches them there...
Thurston, Dylan P.
There is a natural generalization of domino tilings to tilings of a polygon by hexagons,
or, dually, configurations of oriented curves that meet in triples. We show exactly when two such
tilings can be connected by a series of moves analogous to the domino flip move. The triple diagrams
that result have connections to Legendrian knots, cluster algebras, and planar algebras.
Thurston, Dylan P.
There is a natural generalization of domino tilings to tilings of a polygon by hexagons,
or, dually, configurations of oriented curves that meet in triples. We show exactly when two such
tilings can be connected by a series of moves analogous to the domino flip move. The triple diagrams
that result have connections to Legendrian knots, cluster algebras, and planar algebras.
Snyder, Noah
Mednykh [Me78] proved that for any finite group G and any orientable surface S, there is a
formula for $# \mathrm{Hom}(\pi_1(S),G)$ in terms of the Euler characteristic of $S$ and the dimensions of the irreducible
representations of $G$. A similar formula in the nonorientable case was proved by Frobenius and Schur [FS06].
Both of these proofs use character theory and an explicit presentation for $\pi_1$. These results have been
reproven using quantum field theory ([FQ93], [MY05], and others). Here we present a greatly simplified
proof of these results which uses only elementary topology and combinatorics. The main tool is an elementary
invariant of surfaces attached to...
Snyder, Noah
Mednykh [Me78] proved that for any finite group G and any orientable surface S, there is a
formula for $# \mathrm{Hom}(\pi_1(S),G)$ in terms of the Euler characteristic of $S$ and the dimensions of the irreducible
representations of $G$. A similar formula in the nonorientable case was proved by Frobenius and Schur [FS06].
Both of these proofs use character theory and an explicit presentation for $\pi_1$. These results have been
reproven using quantum field theory ([FQ93], [MY05], and others). Here we present a greatly simplified
proof of these results which uses only elementary topology and combinatorics. The main tool is an elementary
invariant of surfaces attached to...
Schücker, Thomas
The Bianchi I metric describes a homogeneous, but anisotropic universe and is commonly used
to fit cosmological data. A fit to the angular distribution of 740 supernovae of type Ia with measured redshift
and apparent luminosity is presented. It contains an intriguing, yet non-significant signal of a preferred
direction in the sky. The Large Synoptic Survey Telescope being built in Chile should measure some 500 000
supernovae within the next 20 years and verify or falsify this signal.
Schücker, Thomas
The Bianchi I metric describes a homogeneous, but anisotropic universe and is commonly used
to fit cosmological data. A fit to the angular distribution of 740 supernovae of type Ia with measured redshift
and apparent luminosity is presented. It contains an intriguing, yet non-significant signal of a preferred
direction in the sky. The Large Synoptic Survey Telescope being built in Chile should measure some 500 000
supernovae within the next 20 years and verify or falsify this signal.
Saini, Sohan Lal
In an attempt to find analogues, for higher relative commutants, of the Bose-Mesner algebra structure
on the second relative commutant of a spin-model subfactor, we find that there do indeed exist other
algebra structures on the higher relative commutants of any subfactor planar algebra which are induced
by the action of tangles; in fact, we show they can only arise in the obvious fashion.
Saini, Sohan Lal
In an attempt to find analogues, for higher relative commutants, of the Bose-Mesner algebra structure
on the second relative commutant of a spin-model subfactor, we find that there do indeed exist other
algebra structures on the higher relative commutants of any subfactor planar algebra which are induced
by the action of tangles; in fact, we show they can only arise in the obvious fashion.
Morrison, Scott
I present a method of calculating the coefficients appearing in the Jones-Wenzl projections in
the Temperley-Lieb algebras. It essentially repeats the approach of Frenkel and Khovanov in [4] published in
1997. I wrote this note mid-2002, not knowing about their work, but then set it aside upon discovering their
article.
¶Recently I decided to dust it off and place it on the arXiv — hoping the self-contained and detailed proof I
give here may be useful.
¶The proof is based upon a simplification of the Wenzl recurrence relation. I give an example calculation,
and compare this method to the formula announced by Ocneanu [13] and partially proved...
Morrison, Scott
I present a method of calculating the coefficients appearing in the Jones-Wenzl projections in
the Temperley-Lieb algebras. It essentially repeats the approach of Frenkel and Khovanov in [4] published in
1997. I wrote this note mid-2002, not knowing about their work, but then set it aside upon discovering their
article.
¶Recently I decided to dust it off and place it on the arXiv — hoping the self-contained and detailed proof I
give here may be useful.
¶The proof is based upon a simplification of the Wenzl recurrence relation. I give an example calculation,
and compare this method to the formula announced by Ocneanu [13] and partially proved...
Liu, Zhengwei; Penneys, David
We state a conjecture for the formulas of the depth 4 low-weight rotational eigenvectors and their
corresponding eigenvalues for the $3^G$ subfactor planar algebras. We prove the conjecture in the case
when $|G|$ is odd. To do so, we find an action of $G$ on the reduced subfactor planar algebra at $f^(2)$,
which is obtained from shading the planar algebra of the even half. We also show that this reduced
subfactor planar algebra is a Yang-Baxter planar algebra.
Liu, Zhengwei; Penneys, David
We state a conjecture for the formulas of the depth 4 low-weight rotational eigenvectors and their
corresponding eigenvalues for the $3^G$ subfactor planar algebras. We prove the conjecture in the case
when $|G|$ is odd. To do so, we find an action of $G$ on the reduced subfactor planar algebra at $f^(2)$,
which is obtained from shading the planar algebra of the even half. We also show that this reduced
subfactor planar algebra is a Yang-Baxter planar algebra.
Izumi, Masaki
We classify $C^\ast$ near-group categories by using Vaughan Jones theory of subfactors and the Cuntz
algebra endomorphisms. Our results show that there is a sharp contrast between two essentially different
cases, integral and irrational cases. When the dimension of the unique non-invertible object is an integer,
we obtain a complete classification list, and it turns out that such categories are always group theoretical.
When it is irrational, we obtain explicit polynomial equations whose solutions completely classify the $C^\ast$
near-group categories in this class.
Izumi, Masaki
We classify $C^\ast$ near-group categories by using Vaughan Jones theory of subfactors and the Cuntz
algebra endomorphisms. Our results show that there is a sharp contrast between two essentially different
cases, integral and irrational cases. When the dimension of the unique non-invertible object is an integer,
we obtain a complete classification list, and it turns out that such categories are always group theoretical.
When it is irrational, we obtain explicit polynomial equations whose solutions completely classify the $C^\ast$
near-group categories in this class.
Hayes, Ben
Motivated by our previous results, we investigate structural properties of probability measurepreserving
actions of sofic groups relative to their Pinsker factor. We also consider the same properties relative
to the Outer Pinsker factor, which is another generalization of the Pinsker factor in the nonamenable case. The
Outer Pinsker factor is motivated by entropy in the presence, which fixes some of the “pathological” behavior
of sofic entropy: namely increase of entropy under factor maps. We show that an arbitrary probability
measure-preserving action of a sofic group is mixing relative to its Pinsker and Outer Pinsker factors and, if
the group is nonamenable, it has spectral gap relative...
Hayes, Ben
Motivated by our previous results, we investigate structural properties of probability measurepreserving
actions of sofic groups relative to their Pinsker factor. We also consider the same properties relative
to the Outer Pinsker factor, which is another generalization of the Pinsker factor in the nonamenable case. The
Outer Pinsker factor is motivated by entropy in the presence, which fixes some of the “pathological” behavior
of sofic entropy: namely increase of entropy under factor maps. We show that an arbitrary probability
measure-preserving action of a sofic group is mixing relative to its Pinsker and Outer Pinsker factors and, if
the group is nonamenable, it has spectral gap relative...
Hartglass, Michael
Hartglass, Michael