منابع مشابه
Lifting in Z
Formal notations such as Z provide powerful support for writing clear specifications, and for undertaking proofs of properties of those specifications. In this paper, we explore one particular style of specification, with applications in control theory and real-time specification. The notation we define permits the accurate description of concepts in these fields without significant overhead or...
متن کاملLifting Representations of Z - Groups
Let K be the kernel of an epimorphism G→ Z, where G is a finitely presented group. If K has infinitely many subgroups of index 2, 3 or 4, then it has uncountably many. Moreover, if K is the commutator subgroup of a classical knot group G, then any homomorphism from K onto the symmetric group S2 (resp. Z3) lifts to a homomorphism onto S3 (resp. alternating group A4).
متن کاملLIFTING SUBGROUPS OF SYMPLECTIC GROUPS OVER Z/lZ
For a positive integer g, let Sp 2g(R) denote the group of 2g × 2g symplectic matrices over a ring R. Assume g ≥ 2. For a prime number l, we show that any closed subgroup of Sp 2g(Zl) that surjects onto Sp2g(Z/lZ) must in fact equal all of Sp2g(Zl). Our result is motivated by group theoretic considerations that arise in the study of Galois representations associated to abelian varieties.
متن کاملClassifying toric and semitoric fans by lifting equations from SL(2, Z)
We present an algebraic method to study four-dimensional toric varieties by lifting matrix equations from the special linear group SL(2, Z) to its preimage in the universal cover of SL(2, R). With this method we recover the classification of two dimensional toric fans, and obtain a description of their semitoric analogue. As an application to symplectic geometry of Hamiltonian systems, we give ...
متن کاملA note on lifting projections
Suppose $pi:mathcal{A}rightarrow mathcal{B}$ is a surjective unital $ast$-homomorphism between C*-algebras $mathcal{A}$ and $mathcal{B}$, and $0leq aleq1$ with $ain mathcal{A}$. We give a sufficient condition that ensures there is a proection $pin mathcal{A}$ such that $pi left( pright) =pi left( aright) $. An easy consequence is a result of [L. G. Brown and G. k. Pedersen, C*-algebras of real...
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ژورنال
عنوان ژورنال: Electronic Notes in Theoretical Computer Science
سال: 2001
ISSN: 1571-0661
DOI: 10.1016/s1571-0661(04)80886-7