Virtual Evidence: A Constructive Semantics for Classical Logics

This article presents a computational semantics for classical logic using constructive type theory. Such semantics seems impossible because classical logic allows the Law of Excluded Middle (LEM), not accepted in constructive logic since it does not have computational meaning. However, the apparently oracular powers expressed in the LEM, that for any proposition P either it or its negation, not P, is true can also be explained in terms of constructive evidence that does not refer to "oracles for truth." Types with virtual evidence and the constructive impossibility of negative evidence provide sufficient semantic grounds for classical truth and have a simple computational meaning. This idea is formalized using refinement types, a concept of constructive type theory used since 1984 and explained here. A new axiom creating virtual evidence fully retains the constructive meaning of the logical operators in classical contexts. Key Words: classical logic, constructive logic, intuitionistic logic, propositions-as-types, constructive type theory, refinement types, double negation translation, computational content, virtual evidenc

Praca socjalna i terapia rodziny: interdyscyplinarne korzenie interwencji w rodzinie

Social work practice takes place between persons in families and other social institutions, such as schools, health systems, welfare systems or courts. Drawing from multi-disciplinary theoretical sources, the article brings together social work and family therapy to develop a contemporary model of social work practice with families. There are five generic principles of family systemic practice: 1) persons are inherently relational; 2) families have resilient strengths; 3) family life cycles proceed systemically generating relational tasks for family members; 4) repetitive family interaction generates relational structures; 5) cultures, as perceived by family members, are themselves in dynamic motion, necessitating a transcultural understanding of family interaction.Praktyka pracy socjalnej odbywa się pomiędzy członkami rodzin a innymi instytucjami społecznymi, takimi jak: szkoły, systemy opieki zdrowotnej, systemy opieki społecznej i sądy. Czerpiąc z multidyscyplinarnych źródeł teoretycznych, artykuł łączy pracę socjalną i terapię rodzinną w celu opracowania współczesnego modelu praktyki pracy socjalnej z rodzinami. Istnieje pięć ogólnych zasad systemowej praktyki rodzinnej: 1) osoby są z natury relacyjne; 2) rodziny mają siły rodzące sprężystość psychiczną; 3) cykle życia rodzinnego postępują systemowo, generując relacyjne zadania dla członków rodziny; 4) powtarzające się interakcje rodzinne generują struktury relacyjne; 5) kultury, postrzegane przez członków rodziny, znajdują się w stanie dynamicznego ruchu, co wymaga transkulturowego zrozumienia interakcji rodziny

Exotic Scalar States in the AdS/CFT Correspondence

We investigate a family of solutions of Type IIb supergravity which asymptotically approach AdS_5 X S^5 but contain a non-constant dilaton and volume scalar for the five-sphere. These solutions preserve an SO(1,3) X SO(6) symmetry. We discuss the solution in the context of the AdS/CFT correspondence, and we find that as well as running coupling from the nontrivial dilaton, the corresponding field theory has no supersymmetry and displays confinement at least for a certain range of parameters.Comment: 18 pages. 3 figures. Revised discussion section, added references. Final version to appear in JHE

Family education and family therapy: tools for relational change

In this paper, I wish to outline the substantive base for family education and family therapy in the necessary interaction of family members to secure uniquely human needs –to create a secure and safe base, to belong, to communicate, to have choices within an ethical, relational framework, to grow, to interact, to care for others and to love. Family interaction, if it is successful, creates the context for human development and human care of vulnerable persons –all of us. I will use these reflections on the substance of family interaction briefly to discuss family therapy and family education and raise questions for further work in this area

Education for social work as a self-regulating profession

The paper was given on 5 April 2000 as an invitational paper at the university of Macerata in Italy upon the opening of their new program preparing for social work (assistence sociale) practice in Italy. The paper discusses models of social work education which would prepare for free-standing, self-regulated practice (una libera professione) of social work, similar to professions of physicians, lawyers, accountants, etc. there is discussion of international models of social work practice, the general scope of work an advanced, specialized practice

Transforming the Academy: Knowledge Formation in the Age of Digital Information

Computer-mediated knowledge formation will profoundly change every academic discipline and pose fundamental challenges to the mission of the modern research university in teaching the new knowledge, securing sound methods for creating it, directing it to our deepest intellectual concerns, and insuring that we become wiser for it. Digital information, now measured in petabytes, is expanding rapidly; already most of it will never be examined by any human. Computers show us where to look and help us see patterns and extract meaning. How will this way of knowing impact the research university as the Age of Digital Information unfolds? To grasp the magnitude of the changes we face, it is important to realize that knowledge created with computer assistance goes well beyond classical knowledge formation rising from computer processing of digital information resources on a scale that could not be achieved by all peoples of the earth acting in concert using all their cognitive powers. Computers change the scale at which resources can be examined, and they already provide sufficient discriminatory powers that scale and speed compensate for their currently limited intelligence as they draw conclusions, make predictions, and participate in discoveries. The academy is not generally aware of the potential of this transformation, although some computer scientists and computational scientist are. The challenge for society is to assimilate digital knowledge and to improve the human condition by its application. We also seek to understand how it will shape our sense of self, individually and collectively as a society and a culture. In all of these tasks, the universities play an indispensable role for which they must prepare

Spin-Two Glueballs, Positive Energy Theorems and the AdS/CFT Correspondence

We determine the spectrum of graviton excitations in the background geometry of the AdS soliton in p+2 dimensions. Via the AdS/CFT correspondence this corresponds to determining the spectrum of spin two excitations in the dual effective p-dimensional field theories For the cases of D3- and M5-branes these are the spin two glueballs of QCD_3 and QCD_4 respectively. For all values of p we find an exact degeneracy of the spectra of these tensor states and certain scalar excitations. Our results also extend the perturbative proof of a positive energy conjecture for asymptotically locally AdS spacetimes (originally proposed for p=3) to an arbritrary number of dimensions.Comment: 25 pages, 3 figure

Generating event logics with higher-order processes as realizers

Our topic is broadening a practical ”proofs-as-programs” method of program development to “proofs-as-processes”. We extend our previous results that implement proofs-as-processes for the standard model of asynchronous message passing computation to a much wider class of process models including the ¼-calculus and other process algebras. Our first result is a general process model whose definition in type theory is interesting in itself both technically and foundationally. Process terms are type free lambda-terms. Typed processes are elements of a co-inductive type. They are higher-order in that they can take processes as inputs and produce them as outputs. A second new result is a procedure to generate event structures over the general process model and then define event logics and event classes over these structures. Processes are abstract realizers for assertions in the event logics over them, and they extend the class of primitively realizable propositions built on the propositions-as-types principle. They also provide a basis for the third new result, showing when programmable event classes generate strong realizers that prevent logical interference as processes are synthesized

Investigating correct-by-construction attack-tolerant systems

Attack-tolerant distributed systems change their protocols on-the-fly in response to apparent attacks from the environment; they substitute functionally equivalent versions possibly more resistant to detected threats. Alternative protocols can be packaged together as a single adaptive protocol or variants from a formal protocol library can be sent to threatened groups of processes. We are experimenting with libraries of attack-tolerant protocols that are correct-by-construction and testing them in environments that simulate specified threats, including constructive versions of the famous FLP imaginary adversary against fault-tolerant consensus. We expect that all variants of tolerant protocols are automatically generated and accompanied by machine checked proofs that the generated code satisfies formal properties.DARP