Satisfiability Modulo Theories (SMT) problem is a decision problem for logical first order formulas with respect to combinations of background theories such as: arithmetic, bit-vectors, arrays, and uninterpreted functions. Z3 is a new and efficient SMT Solver freely available from Microsoft Research. It is used in various software verification and analysis applications.

https://link.springer.com/content/pdf/10.1007%2F978-3-540-78800-3_24.pdf

Z3: an efficient SMT solver

Model Checking

The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

https://publications.uni.lu/bitstream/10993/20596/1/survey_on_SDN.pdf

Software-Defined Networking: A Comprehensive Survey

This ebook is the first authorized digital version of Kernighan and Ritchie's 1988 classic, The C Programming Language (2nd Ed.). One of the best-selling programming books published in the last fifty years, "K&R" has been called everything from the "bible" to "a landmark in computer science" and it has influenced generations of programmers. Available now for all leading ebook platforms, this concise and beautifully written text is a "must-have" reference for every serious programmers digital library.

As modestly described by the authors in the Preface to the First Edition, this "is not an introductory programming manual; it assumes some familiarity with basic programming concepts like variables, assignment statements, loops, and functions. Nonetheless, a novice programmer should be able to read along and pick up the language, although access to a more knowledgeable colleague will help."

The C programming language

Software-Defined Networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound APIs, network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms -- with a focus on aspects such as resiliency, scalability, performance, security and dependability -- as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

PROBLEM TO BE SOLVED: To provide a method and a system for controlling which content should be prioritized and duplicated. SOLUTION: A duplicated article set comprises sets of resources. Each resource is related to resource data and resource metadata. In the case of a file-based system, the resource data include a file content and an attribute; and the resource metadata include an additional attribute related for negotiating synchronization during duplication. A special field called a fence value is added to the metadata related to each resource. The fence values are first compared during synchronization. The resource having the maximum fence value includes a content being a control-side content and duplicated. When the fence value is equal to and larger than a specific value, the control-side resource is determined based on other metadata. COPYRIGHT: (C)2005,JPO&NCIPI

Subdivision control of authority of duplicated information by fencing and fencing release

The present technology is generally directed to updating a cloud network. This technology may include generating a set is inequalities based network topology information, shared risk link group information, demand information, and traffic solver parameters. The set of inequalities may also be based upon a model of traffic routing that is based on selection of routes based on dynamic and global traffic engineering. A capacity plan may also be generated based on the set of inequalities and at least one objective. The capacity plan may include a target capacity for each link of the plurality of links in the network.

Apparatus, method, and manufacture for cloud network updating

Modern program analysis and model-based tools are increasingly complex and multi-faceted software systems.However, at their core is invariably a component using logic for describing states and transformations between system states.The system Z3, developed at Microsoft Research, is a Satisfiability Modulo Theories (SMT) solver.It provides logic inference capabilities that are critical for the functionality of these systems.The tutorial exemplifies a number of applications of Z3 at Microsoft.

SMT Solvers for Testing, Program Analysis and Verification at Microsoft

A method for automatically analyzing formulas and adding pattern annotations to quantifiers based on a database of common pattern idioms. The method involves matching base pattern inference for Satisfiability Modulo Theories (SMT) solvers. The method uses a database for fault detection in externally supplied pattern annotated formulas. The method also uses matching code trees to mixed second-order pattern matching.

Matching Based Pattern Inference for SMT Solvers

This paper presents a system for explicit substitutions in Pure Type Systems (PTS). The system allows to solve type checking, type inhabitation, higher-order unification, and type inference for PTS using purely first-order machinery. A novel feature of our system is that it combines substitutions and variable declarations. This allows as a side-effect to type check let-bindings. Our treatment of meta-variables is also explicit, such that instantiations of meta-variables is internalized in the calculus. This produces a confluent λ-calculus with distinguished holes and explicit substitutions that is insensitive to α-conversion, and allows directly embedding the system into rewriting logic.

Nikolaj Bjørner

Papers

Subdivision control of authority of duplicated information by fencing and fencing release

Apparatus, method, and manufacture for cloud network updating

SMT Solvers for Testing, Program Analysis and Verification at Microsoft

Matching Based Pattern Inference for SMT Solvers

Absolute explicit unification