16547244
CMC: A Tool for Compositional Model-Checking of Real-Time Systems
In this paper we present a tool (CMC) for compositional model-checking of real-time systems. CMC is based on a completely different method compared to existing real-time verification tools (HYTECH, KRONOS, UPPAAL). After a description of the method, we illustrate its efficiency by considering two examples: the Fischer’s mutual exclusion protocol and a railroad crossing system.
4574615
As Cheap as Possible: Efficient Cost-Optimal Reachability for Priced Timed Automata
In this paper we present an algorithm for efficiently computing optimal cost of reaching a goal state in the model of Linearly Priced Timed Automata (LPTA). The central contribution of this paper is a priced extension of so-called zones. This, together with a notion of facets of a zone, allows the entire machinery for symbolic reachability for timed automata in terms of zones to be lifted to cost-optimal reachability using priced zones. We report on experiments with a cost-optimizing extension of Uppaal on a number of examples.
8987497
Efficient Timed Reachability Analysis Using Clock Difference Diagrams
One of the major problems in applying automatic verification tools to industrial-size systems is the excessive amount of memory required during the state-space exploration of a model. In the setting of real-time, this problem of state-explosion requires extra attention as information must be kept not only on the discrete control structure but also on the values of continuous clock variables. 
 
In this paper, we exploit Clock Difference Diagrams, CDD's, a BDD-like data-structure for representing and effectively manipulating certain nonconvex subsets of the Euclidean space, notably those encountered during verification of timed automata. 
 
A version of the real-time verification tool Uppaal using CDD's as a compact data-structure for storing explored symbolic states has been implemented. Our experimental results demonstrate significant spacesavings: for eight industrial examples, the savings are in average 42% with moderate increase in runtime. 
 
We further report on how the symbolic state-space exploration itself may be carried out using CDD's.
14315022
Scaling up Uppaal Automatic Verification of Real-Time Systems Using Compositionality and Abstraction
To combat the state-explosion problem in automatic verification, we present a method for scaling up the real-time verification tool UPPAAL by complementing it with methods for abstraction and compositionality. We identify a notion of timed ready simulation which we show is a sound condition for preservation of safety properties between real-time systems, and in addition is a precongruence with respect to parallel composition. Thus, it supports both abstraction and compositionality. We furthermore present a method for automatically testing for the existence of a timed ready simulation between real-time systems using the UPPAAL tool.
12983032
Practical verification of embedded software
Using a new verification algorithm called the compositional backward technique, the authors demonstrate that they can exhaustively verify even the largest industrial applications-comprising more than 1,000 components-in a few minutes on a standard PC.
1457644
Time-Optimal Test Cases for Real-Time Systems
Testing is the primary software validation technique used by industry today, but remains ad hoc, error prone, and very expensive. A promising improvement is to automatically generate test cases from formal models of the system under test.
336650
UPPAAL 4.0
UPPAAL 4.0 is the result of over two and a half years of development and contains many new features, additions to the modeling language, performance improvements, enhancements and polish to the easy to use graphical user interface, and is accompanied by several open source libraries. The tool and libraries are available free of charge for academic, educational and evaluation purposes from http://www.uppaal.com/. We describe three of the new features: user defined functions, priorities and symmetry reduction
36519093
Fair versus Unrestricted Bin Packing
We consider the Unrestricted Bin Packing problem where we have bins of equal size and a sequence of items. The goal is to maximize the number of items that are packed in the bins by an on-line algorithm. We investigate the power of performing admission control on the items, i.e., rejecting items while there is enough space to pack them, versus behaving fairly, i.e., rejecting an item only when there is not enough space to pack it. We show that by performing admission control on the items, we get better performance for various measures compared with the performance achieved on the fair version of the problem. Our main result shows that we can pack 2/3 of the items for sequences in which the optimal can pack all the items.
5370976
Parametric Permutation Routing via Matchings
The problem of routing permutations on graphs via matchings is considered, and we present a general algorithm which can be parameterized by different heuristics. This leads to a framework which makes the analysis simple and local.
39188673
Amortization Results for Chromatic Search Trees, with an Application to Priority Queues
The intention in designing data structures with relaxed balance, such as chromatic search trees, is to facilitate fast updating on shared-memory asynchronous parallel architectures. To obtain this, the updating and rebalancing have been uncoupled, so extensive locking in connection with updates is avoided.
406624
Model Checking Timed Automata with Priorities Using DBM Subtraction
In this paper we describe an extension of timed automata with priorities, and efficient algorithms to compute subtraction on DBMs (difference bounded matrices), needed in symbolic model-checking of timed automata with priorities. The subtraction is one of the few operations on DBMs that result in a non-convex set needing sets of DBMs for representation. Our subtraction algorithms are efficient in the sense that the number of generated DBMs is significantly reduced compared to a naive algorithm. The overhead in time is compensated by the gain from reducing the number of resulting DBMs since this number affects the performance of symbolic model-checking. The uses of the DBM subtraction operation extend beyond timed automata with priorities. It is also useful for allowing guards on transitions with urgent actions, deadlock checking, and timed games.