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Overview
Differential dynamic logic (dL) [27,25] is a logic for specifying and verifying hybrid systems [27,25].
The logic dL can be used to specify correctness properties for hybrid systems given operationally as
The basic idea for dL formulas is to have formulas of the form [α]φ to specify that the hybrid system α always remains within region φ, i.e., all states reachable by following the transitions of hybrid system α statisfy the formula φ. Dually, the dL formula <α>φ expresses that the hybrid system α is able to reach region φ, i.e., there is a state reachable by following the transitions of hybrid system α that statisfies the formula φ. In either case, the hybrid system α is given as a full operational model in terms of a hybrid program. Using other propositional connectives, one can state the following dL formula
In much the same way as finite automata can be represented as whileprograms, or timed automata have a notation as realtime programs, we use a hybrid program notation for hybrid automata. Essentially, hybrid programs are what you get when you add continuous evolutions as a primitive operation to conventional discrete programs or, in fact, your favorite programming language.
Note: The proper typesetting of the name dL for differential dynamic logic is dℒ. In LaTeX, I use the following for typesetting dℒ:
Syntax
Note that the syntax of the differential dynamic logic dL given here uses slightly simplified notation in comparison to the full syntax in KeYmaera verification tool. The notation in KeYmaera uses more escaping of mathematical characters. 
Operators
and Cheat Sheet 
Formulas of dL, with typical names φ and ψ, are defined by the following syntax  
φ ::=  \forall x φ  Universal quantifier: for all real values of x, formula φ holds 
\exists x φ  Existential quantifier: for some real value of x, formula φ holds  
[α] φ  After all runs of hybrid program α, formula φ holds (safety)  
<α> φ  There is at least one run of hybrid program α, after which formula φ holds (liveness)  
!φ  Negation (not)  
φ & ψ  Conjunction (and)  
φ  ψ  Disjunction (or)  
φ > ψ  Implication (implication)  
φ <> ψ  Biimplication (equivalence)  
pred  Real arithmetic predicate expression 
The behaviour of the hybrid system α is specified as a hybrid program, which is, essentially, a program notation for hybrid systems.
Hybrid programs, with typical names α and β, are defined by the following syntax  
α ::=  α; β  Sequential composition following β after α has finished 
α ++ β  Nondeterministic choice following either α or β  
α^{*}  Nondeterministic repetition, repeating α arbitrarily often including 0 times  
x:=t  Discrete assignment/jump assigning the value of t to x  
{x'=t,y'=s, H}  Continuous evolution along differential equation system with terms t,s, optionally with evolution domain H. Systems of differential equations, differentialalgebraic equations, and differential equations with disturbances are possible as well.  
?H  State assertion testing whether formula H is true in current state (otherwise abort)  
where H is a formula of (possibly nonlinear) real arithmetic. 
Verification
Verifying correct functioning of hybrid systems amounts to proving validity of corresponding formulas in differential dynamic logic dL [27,25]. These dL formulas state the desired correctness properties of the hybrid systems under consideration, including safety, liveness, reactivity, and controllability properties. For showing that these systems operate as expected, André Platzer has devised a logical verification calculus [27,25]. 
Operators
and Rules 
Case studies for using differential dynamic logic to verify complex physical systems include studies for the European Train Control System (ETCS) [16] and verification of collision avoidance in aircraft collision avoidance maneuvers [17]. But there are many more case studies.
Differential Invariants, Variants, and Cuts
Advanced verification technology for differential dynamic logics is further based on differential invariants [24,21] that define an induction principle for differential equations [7] Differential variants are a dual proof principle that can be used to prove liveness and progress properties of differential equations without having to solve them. Differential variants have been introduced in 2008 [24] and implemented in KeYmaera as well.
Details and Extensions
This page only shows the simplest version of a simple differential dynamic logic. For more details see this overview of logics for dynamical systems. Full extended syntax of differential dynamic logic dL, including additionally definable operations [14]
 KeYmaera theorem prover for hybrid systems, which implements the dL calculus
 There is an extension called quantified differential dynamic logic (QdL) [13], with which distributed hybrid systems can be verified. This is the first formal verification approach for (dynamic/reconfigurable) distributed hybrid systems, in which participants may appear and disappear during the system evolution.
 There is an extension called stochastic differential dynamic logic (SdL) [10], with which stochastic hybrid systems can be verified.
 Publications related to dL
 There is an extension called differentialalgebraic dynamic logic (DAL) for more general differentialalgebraic programs [24]
 Advanced verification technology for differential dynamic logic is based on differential invariants [24,22,19], which are formulas that remain true along the dynamics of the hybrid system and its differential equations.
 There is a temporal extension called differential temporal dynamic logic (dTL) [28]. Also see further details and extensions in my book [14].
Abstract
Hybrid systems are models for complex physical systems and are defined as dynamical systems with interacting discrete transitions and continuous evolutions along differential equations. With the goal of developing a theoretical and practical foundation for deductive verification of hybrid systems, we introduce a dynamic logic for hybrid programs, which is a program notation for hybrid systems. As a verification technique that is suitable for automation, we introduce a free variable proof calculus with a novel combination of realvalued free variables and Skolemisation for lifting quantifier elimination for real arithmetic to dynamic logic. The calculus is compositional, i.e., it reduces properties of hybrid programs to properties of their parts. Our main result proves that this calculus axiomatises the transition behaviour of hybrid systems completely relative to differential equations. In a case study with cooperating traffic agents of the European Train Control System, we further show that our calculus is wellsuited for verifying realistic hybrid systems with parametric system dynamics.
Keywords: dynamic logic, differential equations, sequent calculus, axiomatisation, automated theorem proving, verification of hybrid systems
[25]Selected Publications
The canonical references on this approach are [25,24,7,14]. Also see publications on hybrid systems logic and the publication reading guide.
Sarah M. Loos, David Witmer, Peter Steenkiste and André Platzer.
Efficiency analysis of formally verified adaptive cruise controllers.
In Andreas Hegyi and Bart De Schutter, editors, 16th International IEEE Conference on Intelligent Transportation Systems, ITSC'13, The Hague, Netherlands, Proceedings, 2013. © IEEE
[bib  pdf  doi  study  abstract]

Stefan Mitsch, Khalil Ghorbal, and André Platzer.
On provably safe obstacle avoidance for autonomous robotic ground vehicles.
Robotics: Science and Systems, 2013.
[bib  pdf  slides  study  eprint  talk  abstract]

André Platzer.
Dynamic logics of dynamical systems.
arXiv 1205.4788, May 2012.
[bib  pdf  arXiv  abstract]

André Platzer.
A differential operator approach to equational differential invariants.
In Lennart Beringer and Amy Felty, editors, Interactive Theorem Proving, International Conference, ITP 2012, August 1315, Princeton, USA, Proceedings, volume 7406 of LNCS, pages 2848. Springer, 2012. © SpringerVerlag
Invited paper.
[bib  pdf  doi  slides  abstract]

André Platzer.
The structure of differential invariants and differential cut elimination.
Logical Methods in Computer Science, 8(4), pages 138, 2012.
[bib  pdf  doi  eprint  arXiv  abstract]

André Platzer.
Logics of dynamical systems.
ACM/IEEE Symposium on Logic in Computer Science, LICS 2012, June 25–28, 2012, Dubrovnik, Croatia, pages 1324. IEEE 2012. © IEEE
Invited paper.
[bib  pdf  doi  slides  abstract]

André Platzer.
The complete proof theory of hybrid systems.
ACM/IEEE Symposium on Logic in Computer Science, LICS 2012, June 25–28, 2012, Dubrovnik, Croatia, pages 541550. IEEE 2012. © IEEE
[bib  pdf  doi  slides  TR  abstract]

André Platzer.
The Complete Proof Theory of Hybrid Systems.
School of Computer Science, Carnegie Mellon University, CMUCS11144, November 2011.
[bib  pdf  LICS'12  abstract]

André Platzer.
The Structure of Differential Invariants and Differential Cut Elimination.
School of Computer Science, Carnegie Mellon University, CMUCS11112, April 2011.
[bib  pdf  arXiv  LMCS  abstract]

André Platzer.
Stochastic differential dynamic logic for stochastic hybrid programs.
In Nikolaj Bjørner and Viorica SofronieStokkermans, editors, International Conference on Automated Deduction, CADE'11, Wroclaw, Poland, Proceedings, volume 6803 of LNCS, pages 431445. Springer, 2011. © SpringerVerlag
[bib  pdf  doi  slides  TR  abstract]

André Platzer.
Logic and compositional verification of hybrid systems.
In Ganesh Gopalakrishnan and Shaz Qadeer, editors, Computer Aided Verification, CAV 2011, Snowbird, UT, USA, Proceedings, volume 6806 of LNCS, pages 2843. Springer, 2011. © SpringerVerlag
Invited tutorial.
[bib  pdf  doi  slides  abstract]

André Platzer.
Quantified differential invariants.
In Emilio Frazzoli and Radu Grosu, editors, Proceedings of the 14th ACM International Conference on Hybrid Systems: Computation and Control, HSCC 2011, Chicago, USA, April 1214, Pages 6372. ACM, 2011. © ACM
[bib  pdf  doi  slides  abstract]

André Platzer.
Quantified differential dynamic logic for distributed hybrid systems.
In Anuj Dawar and Helmut Veith, editors, Computer Science Logic, 19th EACSL Annual Conference, CSL 2010, Brno, Czech Republic, August 2327, 2010. Proceedings, volume 6247 of LNCS, pages 469483. Springer, 2010. © SpringerVerlag
[bib  pdf  doi  slides  TR  abstract]

André Platzer.
Logical Analysis of Hybrid Systems: Proving Theorems for Complex Dynamics.
Springer, 2010. 426 p. ISBN 9783642145087.
[bib  book  eBook  doi  web]

André Platzer.
Differential dynamic logic: Automated theorem proving for hybrid systems.
Künstliche Intelligenz, 24(1), pages 7577, 2010. © SpringerVerlag
Invited paper.
[bib  doi  abstract]

André Platzer and JanDavid Quesel.
European Train Control System: A case study in formal verification.
In Karin Breitman and Ana Cavalcanti, editors, 11th International Conference on Formal Engineering Methods, ICFEM, Rio de Janeiro, Brasil, Proceedings, volume 5885 of LNCS, pages 246265. Springer, 2009. © SpringerVerlag
[bib  pdf  doi  slides  study  TR  abstract]

André Platzer and Edmund M. Clarke.
Formal verification of curved flight collision avoidance maneuvers: A case study.
In Ana Cavalcanti and Dennis Dams, editors, 16th International Symposium on Formal Methods, FM, Eindhoven, Netherlands, Proceedings, volume 5850 of LNCS, pages 547562. Springer, 2009. © SpringerVerlag
This paper was awarded the FM Best Paper Award.
[bib  pdf  doi  slides  study  TR  abstract]

André Platzer.
Verification of cyberphysical transportation systems.
IEEE Intelligent Systems, 24(4), pages 1013, Jul/Aug, 2009. © IEEE.
Invited paper.
[bib  doi  abstract]

André Platzer and Edmund M. Clarke.
Computing differential invariants of hybrid systems as fixedpoints.
Formal Methods in System Design, 35(1), pages 98120, 2009. © SpringerVerlag
Special issue for selected papers from CAV'08.
[bib  pdf  doi  study  abstract]

André Platzer and JanDavid Quesel.
KeYmaera: A hybrid theorem prover for hybrid systems.
In Alessandro Armando, Peter Baumgartner, and Gilles Dowek, editors, Automated Reasoning, Fourth International Joint Conference, IJCAR 2008, Sydney, Australia, Proceedings, volume 5195 of LNCS, pages 171178. Springer, 2008. © SpringerVerlag
[bib  pdf  doi  slides  tool  abstract]

André Platzer.
Differential Dynamic Logics: Automated Theorem Proving for Hybrid Systems.
PhD Thesis, Department of Computing Science, University of Oldenburg, 2008.
ACM Doctoral Dissertation Honorable Mention Award in 2009.
Extended version appeared as book Logical Analysis of Hybrid Systems: Proving Theorems for Complex Dynamics, Springer, 2010.
[bib  pdf  eprint  book  doi  web  abstract  slides]

André Platzer and Edmund M. Clarke.
Computing differential invariants of hybrid systems as fixedpoints.
In Aarti Gupta and Sharad Malik, editors, Computer Aided Verification, CAV 2008, Princeton, USA, Proceedings, volume 5123 of LNCS, pages 176189, Springer, 2008. © SpringerVerlag
[bib  pdf  doi  slides  study  TR  abstract]

André Platzer and Edmund M. Clarke.
Computing Differential Invariants of Hybrid Systems as Fixedpoints.
School of Computer Science, Carnegie Mellon University, CMUCS08103, Feb, 2008.
[bib  pdf  CAV'08  abstract]

André Platzer.
Differentialalgebraic dynamic logic for differentialalgebraic programs.
Journal of Logic and Computation, 20(1), pages 309352, 2010. Advance Access published on November 18, 2008 by Oxford University Press.
[bib  pdf  doi  study  abstract]

André Platzer.
Differential dynamic logic for hybrid systems.
Journal of Automated Reasoning, 41(2), pages 143189, 2008. © SpringerVerlag
[bib  pdf  doi  study  abstract]

André Platzer.
Combining deduction and algebraic constraints for hybrid system analysis.
In Bernhard Beckert, editor, 4th International Verification Workshop, VERIFY'07, Workshop at Conference on Automated Deduction (CADE), Bremen, Germany, CEUR Workshop Proceedings, 259:164178, 2007.
[bib  pdf  slides  abstract]

André Platzer.
Differential dynamic logic for verifying parametric hybrid systems.
In Nicola Olivetti, editor, Automated Reasoning with Analytic Tableaux and Related Methods, International Conference, TABLEAUX 2007, Aix en Provence, France, July 36, 2007, Proceedings, volume 4548 of LNCS, pages 216232. Springer, 2007. © SpringerVerlag
This paper was awarded the TABLEAUX Best Paper Award.
[bib  pdf  doi  slides  study  TR  abstract]

André Platzer.
A temporal dynamic logic for verifying hybrid system invariants.
In Sergei Artemov and Anil Nerode, editors, Logical Foundations of Computer Science, International Symposium, LFCS 2007, New York, USA, Proceedings, volume 4514 of LNCS, pages 457471. Springer, 2007. © SpringerVerlag
[bib  pdf  doi  slides  study  TR  abstract]

André Platzer.
Differential logic for reasoning about hybrid systems.
In Alberto Bemporad, Antonio Bicchi, and Giorgio Buttazzo, editors, Hybrid Systems: Computation and Control, 10th International Conference, HSCC 2007, Pisa, Italy, Proceedings, volume 4416 of LNCS, pages 746749. Springer, 2007. © SpringerVerlag
[bib  pdf  doi  poster  abstract]

André Platzer.
Differential logic for reasoning about hybrid systems.
In Alberto Bemporad, Antonio Bicchi, and Giorgio Buttazzo, editors, Hybrid Systems: Computation and Control, 10th International Conference, HSCC 2007, Pisa, Italy, Proceedings, volume 4416 of LNCS, pages 746749. Springer, 2007. © SpringerVerlag
[bib  pdf  doi  poster  abstract]

André Platzer.
Towards a hybrid dynamic logic for hybrid dynamic systems.
In Patrick Blackburn, Thomas Bolander, Torben Braüner, Valeria de Paiva, and Jørgen Villadsen, editors, Proc., International Workshop on Hybrid Logic, HyLo 2006, Seattle, USA, Electr. Notes Theor. Comput. Sci. 174(6):6377, 2007.
[bib  pdf  doi  slides  abstract]
For full details, please see my List of Publications.
There also is a verification tool implementation of dL in a theorem prover, which is called KeYmaera [20].