We report on an “anti-Gleason” phenomenon in classical mechanics: in contrast with the quantum case, the algebra of classical observables can carry a non-linear quasi-state, a monotone functional which is linear on all subspaces generated by Poisson-commuting functions. We present an example of such a quasi-state in the case when the phase space is the 2-sphere. This example lies in the intersection of two seemingly remote mathematical theories—symplectic topology and the theory of topological quasi-states. We use this quasi-state to estimate (...) the error of the simultaneous measurement of non-commuting Hamiltonians. (shrink)

The authors of this article apply systemic and comparative methods in order to discuss the key criteria of hardship as a legal institute, i.e. a fundamental alteration of the contractual equilibrium. The authors focus on modern regulations, such as those established in the Principles of International Commercial Contracts and other international contract restatements. The UNIDROIT Principles and other legal instruments usually quite abstractly define the criterion of fundamental alteration; thus further input is necessary in order to reveal the more precise (...) requirements of hardship. The authors of this article provide such an input by conducting a comparative research of the most prominent legal doctrine and case law. (shrink)

The authors of this article use systemic, comparative and historical methods to review the most representative legal systems – rench, English and German – and analyse how these legal systems deal with the effects of change in circumstances on the performance of a contract. The authors also discuss solutions adopted by scholar groups working on supranational contract law (soft law) instruments, namely, UNIDROIT Principles of International Commercial Contracts and Principles of European Contract Law, stressing that these sets of principles have (...) significantly affected Lithuanian contract law provisions on changed circumstances. The authors concisely evaluate the case law of the Supreme Court of Lithuania on the application of the provisions on change in circumstances and their effect on the performance of a contract. (shrink)