Invited Talk: Towards a Principled Multi-Language Infrastructure

AbstractSun's Java architecture introduced a safe virtual machine (VM) in which an ensemble of software components developed independently could smoothly interoperate. The goal of Microsoft's Common Language Runtime (CLR) is to generalize this approach and allow components in many source languages to interoperate safely. CLR supports flexible interoperation by compiling various source languages into a common intermediate language and by using a unified type system. However, the type system in CLR (and Java VM) enforces only conventional type safety in an object-oriented system. Therefore, higher-level specifications (e.g., resource bounds, generalized access control, formal software protocols) cannot be enforced. Because conventional type systems are too inflexible for real applications, developers often bypass the type system, producing code that steps outside the managed part of the VM; such components cannot be verified.At Yale we have been developing typed common intermediate languages (named FLINT) that can support safely not only the standard object-oriented model, but also higher-order generic (polymorphic) programming and Java-style reflection (introspection). Unlike CLR, our type system is independent of any particular programming model, yet it is capable of expressing all valid propositions and proofs in higher-order predicate logic (so it can be used to capture and verify advanced program properties). The rich type system of FLINT makes it possible to typecheck both compiler intermediate code and low level machine code; this allows typechecking to take place at any phase of compilation, even after optimizations and register allocation. It also leads to a smaller and more extensible VM because low-level native routines that would otherwise be in VM can now be verified and moved into a certified library. This talk describes our vision of the FLINT system, outline our approach to its design, and survey the technologies that can be brought to support its implementation

Diffeomorphism Invariance of Geometric Descriptions of Palatini and Ashtekar Gravity

In this paper, we explicitly prove the presymplectic forms of the Palatini and Ashtekar gravity to be zero along gauge orbits of the Lorentz and diffeomorphism groups, which ensures the diffeomorphism invariance of these theories.Comment: Latex, 6 page

Effect of Earth's rotation on the trajectories of free-fall bodies in Equivalence Principle Experiment

Owing to Earth's rotation a free-fall body would move in an elliptical orbit rather than along a straight line forward to the center of the Earth. In this paper on the basis of the theory for spin-spin coupling between macroscopic rotating bodies we study violation of the equivalence principle from long-distance free-fall experiments by means of a rotating ball and a non-rotating sell. For the free-fall time of 40 seconds, the difference between the orbits of the two free-fall bodies is of the order of 10^{-9}cm which could be detected by a SQUID magnetometer owing to such a magnetometer can be used to measure displacements as small as 10^{-13} centimeters.Comment: 6 pages, 4 figure

Determinant Representation of Correlation Functions for the Uq(gl(1∣1))U_q(gl(1|1)) Free Fermion Model

With the help of the factorizing $F$-matrix, the scalar products of the $U_q(gl(1|1))$ free fermion model are represented by determinants. By means of these results, we obtain the determinant representations of correlation functions of the model.Comment: Latex File, 20 pages, V.3: some discussions are added, V.4 Reference update, this version will appear in J. Math. Phy

Drinfeld twists and algebraic Bethe ansatz of the supersymmetric model associated with Uq(gl(m∣n))U_q(gl(m|n))

We construct the Drinfeld twists (or factorizing $F$-matrices) of the supersymmetric model associated with quantum superalgebra $U_q(gl(m|n))$, and obtain the completely symmetric representations of the creation operators of the model in the $F$-basis provided by the $F$-matrix. As an application of our general results, we present the explicit expressions of the Bethe vectors in the $F$-basis for the $U_q(gl(2|1))$-model (the quantum t-J model).Comment: Latex file, 33 pages; V2: minor typos corrected;V3: Reference update, the new version will appear in Commun. Maths. Phys;V4: misprints correcte

Supersymmetric Vertex Models with Domain Wall Boundary Conditions

By means of the Drinfeld twists, we derive the determinant representations of the partition functions for the $gl(1|1)$ and $gl(2|1)$ supersymmetric vertex models with domain wall boundary conditions. In the homogenous limit, these determinants degenerate to simple functions.Comment: 19 pages, 4 figures, to be published in J. Math. Phy