Smullyan's notion of eeectively inseparable pairs of sets is not the best eeec-tive/constructive analog of Kleene's notion of pairs of sets inseparable by a recursive set. We present a corrected notion of eeectively inseparable pairs of sets, prove a characterization of our notion, and show that the pairs of index sets eeectively inseparable in Smullyan's sense are the same as those eeectively ...

Two games are inseparable by semivalues if both games obtain the same allocation whatever semivalue is considered. The problem of separability by semivalues reduces to separability from the null game. For four or more players, the vector subspace of games inseparable from the null game by semivalues contains games different to zero-game. Now, for five or more players, the consideration of a pri...

We study computably enumerable equivalence relations (ceers), under the reducibility R ≤ S if there exists a computable function f such that x R y if and only if f(x) S f(y), for every x, y. We show that the degrees of ceers under the equivalence relation generated by ≤ form a bounded poset that is neither a lower semilattice, nor an upper semilattice, and its first order theory is undecidable....

Abstract Task-based language teaching is considered an effective way to achieve a harmony between grammar and communication. The present study investigates two different ways of teaching modal verbs: task-based versus traditional approaches. To this purpose, an Oxford Placement Test was administered to select 40 homogeneous participants out of a larger population who took this test. The selecte...

During visual category learning, full feedback (e.g., "Wrong, that was a category 4."), relative to minimal feedback (e.g., "Wrong."), enhances performance when the relevant dimensions are separable. This pattern is reversed with inseparable dimensions. Here, the interaction between trial-by-trial feedback and separability of dimensions in the auditory domain is examined. Participants were trai...

this paper provides an analysis of persian verbs within the framework of optimality theory. to be more specific, it mainly cocentrates on past and present stems of persian verbs. since analyzing this subject within the derivational framework would result phonological rules which are not natural, it is analysed by optimality theory which is one of the constraint-based approach. based on this, we...