Higher degrees of distributivity and completeness in Boolean algebras

The Completeness of the Isomorphism Relation for Countable Boolean Algebras

We show that the isomorphism relation for countable Boolean algebras is Borel complete, i.e., the isomorphism relation for arbitrary countable structures is Borel reducible to that for countable Boolean algebras. This implies that Ketonen’s classification of countable Boolean algebras is optimal in the sense that the kind of objects used for the complete invariants cannot be improved in an esse...

the survey of the virtual higher education in iran and the ways of its development and improvement

این پژوهش با هدف "بررسی وضعیت موجود آموزش عالی مجازی در ایران و راههای توسعه و ارتقای آن " و با روش توصیفی-تحلیلی و پیمایشی صورت پذیرفته است. بررسی اسنادو مدارک موجود در زمینه آموزش مجازی نشان داد تعداد دانشجویان و مقاطع تحصیلی و رشته محل های دوره های الکترونیکی چندان مطلوب نبوده و از نظر کیفی نیز وضعیت شاخص خدمات آموزشی اساتید و وضعیت شبکه اینترنت در محیط آموزش مجازی نامطلوب است.

Distributivity and associativity in effect algebras

We prove “large associativity” of the partial sum in effect algebras and present an overview of distributivity-like properties of partial operations ⊕ and in effect algebras with respect to (possibly infinite) suprema and infima and vice versa generalizing several previous results.

Contiguity and Distributivity in The Enumerable Turing Degrees - Corrigendum

Contiguity and Distributivity in the Enumerable Turing Degrees

We prove that a (recursively) enumerable degree is contiguous i it is locally distributive. This settles a twenty-year old question going back to Ladner and Sasso. We also prove that strong contiguity and contiguity coincide, settling a question of the rst author, and prove that no m-topped degree is contiguous, settling a question of the rst author and Carl Jockusch [11]. Finally, we prove som...