Swap Structures Research Articles

Ivlev-Like Modal Logics of Formal Inconsistency Obtained by Fibring Swap Structures

Ivlev-Like Modal Logics of Formal Inconsistency Obtained by Fibring Swap Structures

Balanced-to-Unbalanced Quadrature Couplers With Wide-Band Common-Mode Suppression

In this paper, two types of balanced-to-unbalanced quadrature couplers with six hybrid ports and arbitrary power division ratio are proposed. For Type 1, the quadrature coupler can realize two power division functions, including balanced/unbalanced to balanced-unbalanced-hybrid, and for Type 2, the quadrature coupler contains balanced -to-unbalanced and unbalanced-to-balanced power division functions. To reduce the circuit size, double-sided parallel-strip line (DSPSL) swap structure is used to replace the half-wavelength transmission line, and compact circuit size can be easily achieved. To validate the performance of the quadrature couplers, two types of the balanced-to-unbalanced quadrature couplers centered at 1 GHz with power division ratios 1:1 and 3:1 are fabricated and measured, respectively. The common mode suppression higher than 10 dB (bandwidths over than 176%) can be realized, the isolation and in-band matching level can be also improved.

A Compact Dual-Band Differential Negative Group Delay Circuit With Wideband Common Mode Suppression

A compact dual-band differential negative group delay (DNGD) circuit with wideband common mode suppression is proposed. Two small 180° phase shift swap structures of double-sided parallel striplines (DSPS) are adopted to realize intrinsic wideband common-mode suppression. The dual-band DNGD characteristic is achieved by the DSPS coupled asymmetrically with two different-length open-circuited resonators. The DNGD times and center frequencies of the lower and upper bands can be tuned independently. To verify the proposed DNGD circuit topology, a prototype is designed, fabricated, and measured. From the measured results, DNGD times are −1.60 ns and −1.43 ns at the center frequencies of 1.227 GHz and 1.575 GHz, respectively. The differential insertion loss is lower than 3.55 dB, the differential return loss is larger than 13.3 dB and the common-mode suppression is over 30.8 dB in both DNGD bands.

Non-Deterministic Matrices: Theory and Applications to Algebraic Semantics

AbstractWe call multioperation any operation that return for even argument a set of values instead of a single value. Through multioperations we can define an algebraic structure equipped with at least one multioperation. This kind of structure is called multialgebra. The study of them began in 1934 with the publication of a paper of Marty. In the realm of Logic, multialgebras were considered by Avron and his collaborators under the name of non-deterministic matrices (or Nmatrices) and used as semantics tool for characterizing some logics which cannot be characterized by a single finite matrix. Carnielli and Coniglio introduced the semantics of swap structures for LFIs (Logics of Formal Inconsistency), which are Nmatrices defined over triples in a Boolean algebra, generalizing Avron’s semantics. In this thesis, we will introduce a new method of algebraization of logics based on multialgebras and swap structures that is similar to classical algebraization method of Lindenbaum-Tarski, but more extensive because it can be applied to systems such that some operators are non-congruential. In particular, this method will be applied to a family of non-normal modal logics and to some LFIs that are not algebraizable by the very general techniques introduced by Blok and Pigozzi. We also will obtain representation theorems for some LFIs and we will prove that, within out approach, the classes of swap structures for some axiomatic extensions of mbC are a subclass of the class of swap structures for the logic mbC.Abstract prepared by Ana Claudia de Jesus Golzio.E-mail: anaclaudiagolzio@yahoo.com.brURL: http://repositorio.unicamp.br/jspui/handle/REPOSIP/322436

Weakly Free Multialgebras

In abstract algebraic logic, many systems, such as those paraconsistent logics taking inspiration from da Costa's hierarchy, are not algebraizable by even the broadest standard methodologies, as that of Blok and Pigozzi. However, these logics can be semantically characterized by means of non-deterministic algebraic structures such as Nmatrices, RNmatrices and swap structures. These structures are based on multialgebras, which generalize algebras by allowing the result of an operation to assume a non-empty set of values. This leads to an interest in exploring the foundations of multialgebras applied to the study of logic systems. It is well known from universal algebra that, for every signature \(\Sigma\), there exist algebras over \(\Sigma\) which are absolutely free, meaning that they do not satisfy any identities or, alternatively, satisfy the universal mapping property for the class of \(\Sigma\)-algebras. Furthermore, once we fix a cardinality of the generating set, they are, up to isomorphisms, unique, and equal to algebras of terms (or propositional formulas, in the context of logic). Equivalently, the forgetful functor, from the category of \(\Sigma\)-algebras to Set, has a left adjoint. This result does not extend to multialgebras. Not only multialgebras satisfying the universal mapping property do not exist, but the forgetful functor \(\mathcal{U}\), from the category of \(\Sigma\)-multialgebras to Set, does not have a left adjoint. In this paper we generalize, in a natural way, algebras of terms to multialgebras of terms, whose family of submultialgebras enjoys many properties of the former. One example is that, to every pair consisting of a function, from a submultialgebra of a multialgebra of terms to another multialgebra, and a collection of choices (which selects how a homomorphism approaches indeterminacies), there corresponds a unique homomorphism, what resembles the universal mapping property. Another example is that the multialgebras of terms are generated by a set that may be viewed as a strong basis, which we call the ground of the multialgebra. Submultialgebras of multialgebras of terms are what we call weakly free multialgebras. Finally, with these definitions at hand, we offer a simple proof that multialgebras with the universal mapping property for the class of all multialgebras do not exist and that \(\mathcal{U}\) does not have a left adjoint.

A measure of Turkey's sovereign and banking sector credit risk: Asset swap spreads

The existence of the credit derivatives written on the eurobonds such as credit default swaps or asset swaps allows policymakers and investors to monitor the evolvement of credit risk. However, these instruments are mostly available in advanced economies, whereas the market for credit derivatives in emerging market countries, including Turkey, is limited in terms of liquidity and maturity. In this regard, this study aims to construct a proxy for the credit risk of the Turkish Treasury and banking sector in international markets by calculating asset swap spread for US dollar-denominated fixed coupon eurobonds, which requires a robust estimation of the relevant yield curves. The study firstly presents the estimation of the sovereign and banking sector yield curves and then constructs a synthetic asset swap structure to obtain embedded credit risk premia in the eurobond curves. Our findings show that the proposed credit risk indicator is vastly correlated with credit default swap premium. In addition to this, estimated eurobond curves are also useful for monitoring borrowing cost dynamics of the Turkish Treasury and banking sector in international markets.

Compact balanced bandpass filter based on dual‐sided parallel‐strip line

A novel compact balanced bandpass filter with wideband common mode rejection is proposed in this article. The intrinsic out-of-phase characteristic is realized by the 180° swap structure, which is based on dual-sided parallel-strip line, wideband common mode (CM) rejection can be easily achieved with compact size and simple configuration. Modified coupled line resonator (MCLR) is applied to implement passband response, and MCLR is composed by conventional coupled line terminated with a λ/4 open stub. To validate the performance, one prototype with 20% 3 dB fractional bandwidth center at 2.2 GHz is designed and fabricated, over than 18 dB CM rejection extended to 2.94f0 can be realized, good agreement can be obtained.

High Performance Balanced Bandpass Filters With Wideband Common Mode Suppression

Two compact and high selectivity balanced bandpass filters with excellent common mode rejection are designed in this brief. Compared with the half-wavelength microstrip transmission line, 180° phase shift is realized by two small swap structures, which are composed by double-sided parallel-strip line (DSPSL), and this way can easily realize a wideband common mode rejection with compact circuit size. Two out-of-band transmission zeros are introduced by the dual-mode ring resonator in the first proposed structure; thus, high selectivity can be achieved. In the second filter, shorted/open coupled microstrip lines are added between the dual-mode ring resonator and 180° swap structure, two additional transmission zeros can be achieved. Finally, two prototypes center at 2.2 GHz are fabricated, and the measured 3-dB bandwidths for the differential mode are 23.6% and 11.8%, respectively.

Modern Application of Bai` al-Sarf (Currency Exchange) From Maqasid Al-Shari’ah Perspective: A Scoping Review

Bai’ al-sarf widely known as currency exchange is an important sale contract both in classical and contemporary world. This scoping review looks into the objectives behind the rulings set by the Shari’ah for this sale contract. These objectives are sorted out from the commentaries of the hadith and the deliberations of the jurists through textual analysis method. Some of the modern applications such as T+2 and Islamic Foreign Currency Exchange (FX) Swap structures are briefly juxtaposed against the objectives of bai’ al-sarf we discovered. Objectives of Shari’ah rulings in spot exchange is to avoid falling into the sale of debt against debt (al-kali bi al-kali), prevention of payment delay by one of the counter parties, prevention of conflict between the counter parties, and last not least to avoid falling into exchange contracts that will induce riba. Keywords: Bai’ al-sarf, currency exchange, spot seizing (al-taqabud fi al-majlis), equal counter-values (al-tamathul), sad bab al-niza’ (closing the door of conflict), riba.

First-order swap structures semantics for some logics of formal inconsistency

Abstract The logics of formal inconsistency (LFIs, for short) are paraconsistent logics (i.e. logics containing contradictory but non-trivial theories) having a consistency connective which allows to recover the ex falso quodlibet principle in a controlled way. The aim of this paper is considering a novel semantical approach to first-order LFIs based on Tarskian structures defined over swap structures, a special class of multialgebras. The proposed semantical framework generalizes previous approaches to quantified LFIs presented in the literature. The case of QmbC, the simpler quantified LFI expanding classical logic, will be analyzed in detail. An axiomatic extension of QmbC called $\textbf{QLFI1}_\circ $ is also studied, which is equivalent to the quantified version of da Costa and D’Ottaviano 3-valued logic J3. The semantical structures for this logic turn out to be Tarkian structures based on twist structures. The expansion of QmbC and $\textbf{QLFI1}_\circ $ with a standard equality predicate is also considered.

On-chip mixing of liquids with swap structures written by two-photon polymerization

A fluidic micromixer realized by two-photon polymerization writing is embedded in a predefined microchannel. The micromixer consists of a 3D defined channel system which swaps incoming fluid streams, resulting in laminar alternating streams consisting of the two liquids to be mixed. Due to the shortened diffusion length, mixing times are reduced dramatically to 50 ms or lower. The structure is designed in such a way that the fluidic resistance in each swapper channel is balanced, yielding equal distribution of the alternating streams. The mixer element has a total size of about $$225\times 100\times 50\,\upmu \hbox {m}^{3}$$, fitting exactly in a prefabricated microchannel. The structure is strongly anchored in the channel so that it can handle high flow rates of up to 100 $$\upmu \text {L/min}$$ (corresponding to an average flow velocity of $$400\,\text {mm/s}$$). A benefit of the fabrication method is the short processing time. The writing of one mixer element takes less than $$30\,\text {s}$$, so that a whole wafer can be processed in typically less than one hour.

Swap structures semantics for Ivlev-like modal logics

In 1988, J. Ivlev proposed some (non-normal) modal systems which are semantically characterized by four-valued non-deterministic matrices in the sense of A. Avron and I. Lev. Swap structures are multialgebras (a.k.a. hyperalgebras) of a special kind, which were introduced in 2016 by W. Carnielli and M. Coniglio in order to give a non-deterministic semantical account for several paraconsistent logics known as logics of formal inconsistency, which are not algebraizable by means of the standard techniques. Each swap structure induces naturally a non-deterministic matrix. The aim of this paper is to obtain a swap structures semantics for some Ivlev-like modal systems proposed in 2015 by M. Coniglio, L. Farinas del Cerro and N. Peron. Completeness results will be stated by means of the notion of Lindenbaum–Tarski swap structures, which constitute a natural generalization to multialgebras of the concept of Lindenbaum–Tarski algebras.

Recovery operators, paraconsistency and duality

Abstract There are two foundational, but not fully developed, ideas in paraconsistency, namely, the duality between paraconsistent and intuitionistic paradigms, and the introduction of logical operators that express metalogical notions in the object language. The aim of this paper is to show how these two ideas can be adequately accomplished by the logics of formal inconsistency (LFIs) and by the logics of formal undeterminedness (LFUs). LFIs recover the validity of the principle of explosion in a paraconsistent scenario, while LFUs recover the validity of the principle of excluded middle in a paracomplete scenario. We introduce definitions of duality between inference rules and connectives that allow comparing rules and connectives that belong to different logics. Two formal systems are studied, the logics mbC and mbD, that display the duality between paraconsistency and paracompleteness as a duality between inference rules added to a common core—in the case studied here, this common core is classical positive propositional logic. The logics mbC and mbD are equipped with recovery operators that restore classical logic for, respectively, consistent and determined propositions. These two logics are then combined obtaining a pair of LFI and undeterminedness, namely, mbCD and mbCDE. The logic mbCDE exhibits some nice duality properties. Besides, it is simultaneously paraconsistent and paracomplete, and able to recover the principles of excluded middle and explosion one at a time. The last sections offer an algebraic account for such logics by adapting the swap structures semantics framework of the LFIs the LFUs. This semantics highlights some subtle aspects of these logics, and allows us to prove decidability by means of finite nondeterministic matrices.

Non-deterministic algebraization of logics by swap structures1

AbstractMultialgebras (or hyperalgebras or non-deterministic algebras) have been much studied in mathematics and in computer science. In 2016 Carnielli and Coniglio introduced a class of multialgebras called swap structures, as a semantic framework for dealing with several Logics of Formal Inconsistency (or LFIs) that cannot be semantically characterized by a single finite matrix. In particular, these LFIs are not algebraizable by the standard tools of abstract algebraic logic. In this paper, the first steps towards a theory of non-deterministic algebraization of logics by swap structures are given. Specifically, a formal study of swap structures for LFIs is developed, by adapting concepts of universal algebra to multialgebras in a suitable way. A decomposition theorem similar to Birkhoff’s representation theorem is obtained for each class of swap structures. Moreover, when applied to the 3-valued algebraizable logics J3 and Ciore, their classes of algebraic models are retrieved, and the swap structures semantics become twist structures semantics (as independently introduced by M. Fidel and D. Vakarelov). This fact, together with the existence of a functor from the category of Boolean algebras to the category of swap structures for each LFI (which is closely connected with Kalman’s functor), suggests that swap structures can be seen as non-deterministic twist structures. This opens new avenues for dealing with non-algebraizable logics by the more general methodology of multialgebraic semantics.

A hybrid harmony search algorithm with efficient job sequence scheme and variable neighborhood search for the permutation flow shop scheduling problems

The permutation flow shop scheduling problem (PFSSP), one of the most widely studied production scheduling problems, is a typical NP-hard combinatorial optimization problem. In this paper, a hybrid harmony search algorithm with efficient job sequence mapping scheme and variable neighborhood search (VNS), named HHS, is proposed to solve the PFFSP with the objective to minimize the makespan. First of all, to extend the HHS algorithm to solve the PFSSP effectively, an efficient smallest order value (SOV) rule based on random key is introduced to convert continuous harmony vector into a discrete job permutation after fully investigating the effect of different job sequence mapping schemes. Secondly, an effective initialization scheme, which is based on NEH heuristic mechanism combining with chaotic sequence, is employed with the aim of improving the solution’s quality of the initial harmony memory (HM). Thirdly, an opposition-based learning technique in the selection process and the best harmony (best individual) in the pitch adjustment process are made full use of to accelerate convergence performances and improve solution accuracy. Meanwhile, the parameter sensitivity is studied to investigate the properties of HHS, and the recommended values of parameters adopted in HHS are presented. Finally, by making use of a novel variable neighborhood search, the efficient insert and swap structures are incorporated into the HHS to adequately emphasize local exploitation ability. Experimental simulations and comparisons on both continuous and combinatorial benchmark problems demonstrate that the HHS algorithm outperforms the standard HS algorithm and other recently proposed efficient algorithms in terms of solution quality and stability.

A dual-band power divider using parallel strip line with high isolation

The transmission characteristics of the parallel strip lines (PSLs) are studied. Then a novel dual-band power divider using PSLs is introduced. It consists of four -form arms and one 180° phase swap structure. The -form arms are capable of achieving ideal impedance matching at two different frequency bands with an arbitrary power dividing ratio The 180° phase swap structure is frequency independent, which is used to obtain high port to port isolation. Theoretical analysis and general design procedure of this power divider with arbitrary and (central frequency ratio of two different frequency bands) are presented. Then, a sample operating at 1.3 and 3.5 GHz with and is fabricated and tested. Experimental results show that this power divider operates at the designed dual frequency bands, and the isolation is more than 20 dB. Good agreements among theoretical, simulated, and experimental results are obtained.

Effectively hedging the interest rate risk of wide floating-rate coupon spreads

Bond issuers frequently immunise/hedge their interest rate exposure by means of interest rate swaps (IRS). The receiving leg matches all bond cash flows, while the pay leg requires floating rate coupon payments of form LIBOR plus a spread. The goal of hedging against interest rate risk is only achieved in full if the present value of this spread is zero. Using market data it is shown that under a traditional IRS hedging strategy an investor could still experience significant cash flow losses given a 1 per cent shift in the underlying benchmark yield curve. Consideration is given to the instantaneous interest rate risk of a bond portfolio that allows for general changes in interest rates. Two contributions are made. The paper analyses the size of hedging imperfections arising from the widening of the floating rate spread in a traditional swap contract and subsequently proposes two new practical, effective and analytically tractable swap structures: Structure 1: an improved parallel hedge swap, hedges against parallel shifts of the yield curve; and Structure 2: an improved non-parallel hedge swap, hedges against any movement of the swap curve. Analytical representations of these swaps are provided such that spreadsheet implementations are easily attainable.

A Novel Ultra-Wideband Differential Filter Based on Double-Sided Parallel-Strip Line

In this letter, double-sided parallel-strip line (DSPSL) has been used to build a novel differential filter with ultra- wideband (UWB) response. Swap structures, based on DSPSL, are employed in the design to realize 180° phase shift. So the swap structures can realize the conversion between differential- and common-mode. Utilizing the characteristic, the input common- mode signals will be cancelled at the center of the filter, while the input differential-mode signals can propagate in the proposed filter. The proposed new differential filter was calculated in analytical method, and was simulated by the full-wave electromagnetic simulator, and was validated by the measurement. The last results show they have a good in-band and out-band performance. With fractional bandwidth of 110% centered at 3 GHz, the differential-mode signals can propagate with UWB frequency response, while the common-mode signals are suppressed below -20 dB in the whole frequency band.

Shari'ah Parameters on the Islamic Foreign Exchange Swap as a Hedging Mechanism in Islamic Finance

The Islamic Foreign Exchange Swap (hereafter Islamic FX Swap) is a contract that is designed as a hedging mechanism to minimise market participants’ exposure to market currency exchange rates which are volatile and fluctuating. Although an Islamic FX Swap functions in almost the same way as its conventional counterpart, its structure must not contravene the principles of Shari'ah. In other words, an Islamic FX Swap structure should be free from any elements prohibited by Islam such as usury (riba), gambling (maysir) and excessive ambiguity (gharar). These prohibitions are mainly to promote justice and provide a level playing field in order to protect the interests of and circumvent harm to all parties involved in market transactions, which is in line with the objectives of Shari'ah (maqasid al- Shari'ah). This paper therefore aims to review the structure and mechanism of the Islamic FX Swap as currently offered by many Islamic financial institutions worldwide. Specifically, this paper highlights the Shari'ah parameters and guidelines in structuring an Islamic FX Swap. As will be evident in this paper, this instrument has its own advantages as a risk management tool which appeals to Islamic financial institutions as an instrument to hedge against currency exchange market rate volatility.

A Parallel-Strip Ring Power Divider With High Isolation and Arbitrary Power-Dividing Ratio

In this paper, a new power divider concept, which provides high flexibility of transmission line characteristic impedance and port impedance, is proposed. This power divider is implemented on a parallel-strip line, which is a balanced transmission line. By implementing the advantages and uniqueness of the parallel-strip line, the divider outperforms the conventional divider in terms of isolation bandwidths. A swap structure of the two lines of the parallel-strip line is employed in this design, which is critical for the isolation enhancements. A lumped-circuit model of the parallel-strip swap including all parasitic effects has been analyzed. An equal power divider with center frequency of 2 GHz was designed to demonstrate the idea. The experimental results show that the equal power divider has 96.5% -10-dB impedance bandwidth with more than 25-dB isolation and less than 0.7-dB insertion loss. In order to generalize the concept with an arbitrary power ratio, we also realize unequal power dividers with the same isolation characteristics. The impedance bandwidth of the proposed power divider will increase with the dividing ratio, which is opposite to the conventional Wilkinson power divider. Unequal dividers with dividing ratios of 1 : 2 and 1 : 12 are designed and measured. Additionally, a frequency independent 180 power divider has been realized with less than 2 phase errors.