Position-dependent mass Dirac equation and local Fermi velocity

We present a new approach to study the one-dimensional Dirac equation in the background of a position-dependent mass m. Taking the Fermi velocity vf to be a local variable, we explore the resulting structure of the coupled equations and arrive at an interesting constraint of m turning out to be the inverse square of vf. We address several solvable systems that include the free particle, shifted harmonic oscillator, Coulomb and nonpolynomial potentials. In particular, in the supersymmetric quantum mechanics context, the upper partner of the effective potential yields a new form for an inverse quadratic functional choice of the Fermi velocity.

Storing JWT Token in Local Variables

The article discusses the problem of storing structured information over the Internet (JSON format) in local storage and pieces of information transmitted to the browser from the site visited by the user (cookies), and a method is proposed for storing the JSON web key in a local variable inside the closure (functions that refer to into independent variables). Based on user authorization, the interaction of the JSON web key with the server is shown, and the solution to the main problems of authorization and storage of the token (JWT – JSON Web Token).

Flexible recovery of uniqueness and immutability

© 2018 Elsevier B.V. We present an imperative object calculus where types are annotated with qualifiers for aliasing and mutation control. There are two key novelties with respect to similar proposals. First, the type system is very expressive. Notably, it adopts the recovery approach, that is, using the type context to justify strengthening types, greatly improving its power by permitting to recover uniqueness and immutability properties even in presence of other references. This is achieved by rules which restrict the use of such other references in the portion of code which is recovered. Second, execution is modeled by a non standard operational model, where properties of qualifiers can be directly expressed on source terms, rather than as invariants on an auxiliary structure which mimics physical memory. Formally, this is achieved by the block construct, introducing local variable declarations, which, when evaluated, play the role of store.

An Imperative Pure Calculus

© 2016 The Authors. Published by Elsevier B.V. We present a simple calculus where imperative features are modeled by just rewriting source code terms, rather than by modifying an auxiliary structure which mimics physical memory. Formally, this is achieved by the block construct, introducing local variable declarations, which also plays the role of store when such declarations have been evaluated. In this way, we obtain a language semantics which is more abstract, and directly represents at the syntactic level constraints on aliasing, allowing simpler reasoning about related properties. We illustrate this possibility by a simple extension of the standard type system which assigns a capsule tag to expressions that will reduce to (values representing) isolated portions of store.

Flexible recovery of uniqueness and immutability

© 2018 Elsevier B.V. We present an imperative object calculus where types are annotated with qualifiers for aliasing and mutation control. There are two key novelties with respect to similar proposals. First, the type system is very expressive. Notably, it adopts the recovery approach, that is, using the type context to justify strengthening types, greatly improving its power by permitting to recover uniqueness and immutability properties even in presence of other references. This is achieved by rules which restrict the use of such other references in the portion of code which is recovered. Second, execution is modeled by a non standard operational model, where properties of qualifiers can be directly expressed on source terms, rather than as invariants on an auxiliary structure which mimics physical memory. Formally, this is achieved by the block construct, introducing local variable declarations, which, when evaluated, play the role of store.