bluuebunny/crossref_metadata_2025 huggingface dataset:
Sexually dimorphic dopaminergic circuits determine sex preference
Authors: Wei Anqi , Zhao Anran , Zheng Chaowen , Dong Nan , Cheng Xu , Duan Xueting , Zhong Shuaijie , Liu Xiaoying , Jian Jie , Qin Yuhao , Yang Yuxin , Gu Yuhao , Wang Bianbian , Gooya Niki , Huo Jingxiao , Yao Jingyu , Li Weiwei , Huang Kai , Liu Haiyao , Mao Fenghan , Wang Ruolin , Shao Mingjie , Wang Botao , Zhang Yichi , Chen Yang , Song Qian , Huang Rong , Qu Qiumin , Zhang Chunxiang , Kang Xinjiang , Xu Huadong , Wang Changhe
Published: January 2025

Sociosexual preference is critical for reproduction and survival. However, neural mechanisms encoding social decisions on sex preference remain unclear. In this study, we show that both male and female mice exhibit female preference but shift to male preference when facing survival threats; their preference is mediated by the dimorphic changes in the excitability of ventral tegmental area dopaminergic (VTA
DA
) neurons. In males, VTA
DA
projections to the nucleus accumbens (NAc) mediate female preference, and those to the medial preoptic area mediate male preference. In females, firing-pattern (phasic-like versus tonic-like) alteration of the VTA
DA
-NAc projection determines sociosexual preferences. These findings define VTA
DA
neurons as a key node for social decision-making and reveal the sexually dimorphic DA circuit mechanisms underlying sociosexual preference.
Building materials could store more than 16 billion tonnes of CO
2
annually
Authors: Van Roijen Elisabeth , Miller Sabbie A. , Davis Steven J.
Published: January 2025

Achieving net-zero greenhouse gas emissions likely entails not only lowering emissions but also deploying carbon dioxide (CO
2
) removal technologies. We explored the annual potential to store CO
2
in building materials. We found that fully replacing conventional building materials with CO
2
-storing alternatives in new infrastructure could store as much as 16.6 ± 2.8 billion tonnes of CO
2
each year—roughly 50% of anthropogenic CO
2
emissions in 2021. The total storage potential is far more sensitive to the scale of materials used than the quantity of carbon stored per unit mass of materials. Moreover, the carbon storage reservoir of building materials will grow in proportion to demand for such materials, which could reduce demand for more costly or environmentally risky geological, terrestrial, or ocean storage.
Built to remove carbon
Authors: Bataille Christopher
Published: January 2025

Building materials could facilitate long-term removal of atmospheric carbon dioxide
Grazing can reduce wildfire risk amid climate change
Authors: Pillar Valério D. , Overbeck Gerhard E.
Published: January 2025

Over half of Earth’s land surface is covered with
fire-prone vegetation
, with grassy ecosystems—such as grasslands, savannas, woodlands, and shrublands—being the most
extensive
. In the context of the climate crisis, scientists worldwide are exploring
adaptation
measures to address the heightened fire risk driven by more frequent extreme climatic conditions such as droughts and heatwaves, as well as by
non-native plant invasions
that increased fuel loads and altered fire regimes. Although fire is intrinsic to
grassy ecosystems
, rising exposure to wildfire smoke harms human health and the environment. Here, we argue that grazing management in grassy ecosystems could help reduce wildfire risk and its consequences.
Optimism for a global plastics treaty
Authors: Fletcher Stephen , Evans Tegan
Published: January 2025

The lack of consensus at the United Nations (UN) global plastics treaty negotiations in December may seem like a setback, but declaring the talks a failure is premature. The process has not collapsed but has been extended, with further negotiations anticipated in 2025. This offers a crucial opportunity for the scientific community to assert its role in shaping a robust, evidence-based agreement to address the global plastic pollution crisis. Great progress has been made in building a strong scientific baseline that will be essential to address pivotal areas of contention.
‘Good boring’: How Bluesky is shaping scientists’ discourse
Authors: Kupferschmidt Kai
Published: January 2025

The fast-growing platform may be more equitable than X, but gives scientists a smaller stage
The association of SLC16A1 (MCT1) gene polymorphism with body composition changes during weight loss interventions: A randomized trial with sex-dependent analysis
Authors: Cupeiro Rocío , Benito Pedro J. , Amigo Teresa , González-Lamuño Domingo
Published: January 2025

Monocarboxylates, transported by monocarboxylate transporters (MCTs), have been proposed to influence energy homeostasis and exhibit altered metabolism during exercise. This study investigated the association between the Asp490Glu (T1470A) (rs1049434) polymorphism of the SLC16A1 ( MCT1) gene and changes in body composition in males and females with overweight or obesity. The 173 participants (56.6% females) completed a 6-month randomized controlled trial, being assigned to the Supervised Exercise group (strength, endurance, or strength plus endurance training) or the Physical Activity (PA) Recommendations group. Participants were genotypically categorized as Asp/Asp (TT), Asp/Glu (TA), or Glu/Glu (AA). ANCOVA analysis showed main effects for genotype and interaction genotype × group ( p < 0.05) for several variables, especially in females. Asp/Asp (TT) females showed greater reductions in total fat mass (−29.30 ± 8.75% change), percentage of body fat (−17.50 ± 8.06% change), and body weight (−13.90 ± 2.62% change) compared with Glu/Glu (AA) ( p ≤ 0.020; d ≥ 0.18) and Asp/Glu (TA) ( p ≤ 0.050; d ≥ 0.16) females, but only within the PA Recommendations group. Data indicated higher decreases in lean body mass of the Asp/Asp (TT) compared to Glu/Glu (AA) in females ( p = 0.067, η2 p = 0.067) and to Asp/Glu (TA) in males ( p = 0.026; η2 p = 0.101). Our investigation suggests an association of the single-nucleotide polymorphism with body composition changes especially in females following exercise recommendations, highlighting the importance of supervised training to offset genetic predisposition for different weight loss. Differences in males only appeared for lean body mass, suggesting sex differences for this genetic association. The study underscores the potential influence of MCT1 functionality on human adaptations to weight loss interventions. ClinicalTrials.gov information: registry name, Nutrition and Physical Activity for Obesity (PRONAF); registration number, NCT01116856.
Biomass allocation and growth of young black spruce (Picea mariana (Mill.) B.S.P.) trees
Authors: Krause Cornelia , Plourde Pierre-Y. , Marty Charles
Published: January 2025

Accurately predicting biomass allocation to below- versus above-ground tree parts is crucial in estimating carbon stocks in forest ecosystems. A 9-year outdoor experiment was conducted to analyze the variations in biomass allocation in below- and above-ground parts in black spruce trees growing at the edge or at the center of a raised garden bed. Dry biomass, length, and radial growth of stems, branches, and roots were measured as well as the annual above-ground growth for the five most recent years prior to harvesting. We found that more than 90% of dry biomass was allocated to the above-ground tree parts whereas less than 10% was allocated to the root system. Strong correlations were found between the different tree parts regardless of the tree’s position in the delimited growth area. Annual growth variables declined from 2018 to 2022, likely due to increased competition for resources. The dry biomass of the woody root and the root surface close to the stem were well correlated to the above-ground tree parts (varying between 45% and 95%). Thus, the strong link between the root system and the above tree parts is confirmed.
A data compilation and synthesis of the impacts of seismic surveys on surface soil properties in boreal Alberta, Canada
Authors: Davies Marissa A. , Davidson Scott J. , Deane Patrick J. , Filicetti Angelo , Ketcheson Scott , Korsah Percy , Kleinke Kimberly , Nielsen Scott E. , Schmidt Megan A. , Tabassum Nazia , Waddington James M. , Weiland Lelia , Wilkinson Sophie , Strack Maria
Published: January 2025

Linear clearings of vegetation to perform geophysical surveys, called seismic lines, are created for oil and gas exploration in boreal Canada and often persist on the landscape for decades after disturbance. Therefore, an assessment of environmental conditions on seismic lines is needed to inform restoration efforts. This study aimed to compile surface soil properties (upper 5–15 cm; dry bulk density, organic matter content, organic matter bulk density, volumetric water content, and water content by mass) on and off seismic lines across upland, transitional, and peatland ecosystems in northern Alberta, Canada ( N = 1638). Soil properties differ between seismic line and reference samples, especially on older “conventional” lines. Changes included higher dry bulk density, lower organic matter content, and elimination of microtopographic variability. Changes in dry bulk density can, in part, be explained by a reduction in organic matter content, but altered carbon cycling and/or compaction are also important. Restoration techniques such as inverted mounding create an entirely distinct soil condition, with higher mean bulk densities and lower organic matter contents than both on and off seismic lines. Therefore, an assessment of microtopographic recovery should be conducted before prescribing restoration treatments to limit further degradation of soil structure.
Seasonal Bird Communities in Shelterwood Harvests and Unmanaged Mature Forest
Authors: Greenberg Cathryn , Woodbridge Margaret , Whitehead Maria , Lanham Joseph Drew , Kwit Charles , Tomcho Joseph
Published: January 2025

Effective bird conservation planning requires consideration of year-round habitat requirements. We evaluated how bird communities differed across seasons, and between young shelterwood (SW) and unmanaged mature (M) hardwood forests over 8 years. We detected 3,952 individuals of 82 bird species within transects. Total abundance, richness, and diversity were highest in summer and lowest in winter. Richness was greater in SW than M during all seasons; abundance and diversity were greater in SW during summer, fall, and spring. Community composition differed between SW and M during all seasons except winter. Within seasons, abundance of most analyzed species was greater in SW than M or similar between the treatments. In SW young forest habitat suitability for most species (except indigo buntings) persisted for at least 8 years. Residency guilds and some species showed greater habitat selectivity in some seasons (heavier use of SW) than others (similar use of both SW and M). Our study illustrates the important role of young forests in promoting bird diversity year-round. However, knowledge gaps remain regarding bird use of all forest age-classes during all seasons, and how long dynamically changing young forests support more birds and bird species than mature forest during non-breeding seasons.
Casimir effect with an unstable mode
Authors: Bordag M. , Pirozhenko I. G.
Published: January 2025

In this paper, we consider the Casfimir effect in a (1+1)-dimensional model with a critical mode. Such a mode gives rise to a condensate described by the nonlinear Gross–Pitaevskii equation. In the condensate, there are two sources of the Casimir force; one is the conventional one resulting from the fluctuations, the other follows from the condensate. We consider three simple models that allow for condensate solutions in terms of elliptic Jacobi functions. We also investigate a method for obtaining approximate solutions and show its range of applicability. In all three examples, we compute the condensate energy. In one example with a finite interval with Robin boundary conditions on one side and Dirichlet conditions on the other side, we calculate the vacuum energy and the Casimir force. There is a competition between the forces from the condensate and the fluctuations. We mention that the force from the condensate is always repulsive.
Topologically dynamical complex objects and structure scalars
Authors: Yousaf Z. , Ganesan T. , Almutairi Bander , Nasir M. M. M.
Published: January 2025

In this study, we explore topologically spherical relativistic objects and analyze the factors that are involved in maintaining the smooth composition of anisotropic content. The corresponding field equations resulting from this extension show a different behavior due to the higher-order correction terms. We study the role of structure scalar in the possible modeling of complex objects in a well-known way, discussed by [L. Herrera, A. Di Prisco and J. Ospino, Phys. Rev. D 98 (2018) 104059]. After orthogonally splitting the curvature tensor, the associated dynamical equations are evaluated. We examine the complexity of the pattern of evolution by considering the homologous constraint. Furthermore, in the presence and absence of dissipation, the behavior, characteristics, and stability of the self-gravitating structures are analyzed. It is inferred that correction terms are trying to disturb the usual scenario of the homologous evolution of the relativistic dynamical system.
The origin of dark matter and the cosmological constant
Authors: Marsh Gerald E.
Published: January 2025

The concept of exotic charged dust is introduced here to represent dark matter. The term “exotic” means that the dust is not composed of normal matter, and the charge — for lack of a better term — is not an electric charge. It is also shown that the often-used approximate expression for dark matter density corresponds to an exact solution of the coupled Einstein–Maxwell equations for charged dust. The Einstein field equations tell us that for a flat universe, the cosmological constant acts as a gravitating negative energy distribution that is gravitationally repulsive; following Schwinger, it is shown that the vacuum must have a negative energy spectrum if QFT is to be gauge invariant.
A Stochastic Model of Stress Range for Heavy-Haul Railway Steel Bridges and Their Probability Characteristics
Authors: Zhang Sheng-Wang , Lu Zhao-Hui , Li Chun-Qing
Published: January 2025

Fatigue of heavy-haul railway bridges caused by large and frequent cyclic loads has become a serious concern to all stakeholders of the bridges. The dynamics, temporal, and stochastic features of such loads make it very difficult to assess the fatigue performance of the bridges. The aim of this study is to propose a stochastic analysis method of stress range for heavy-haul railway bridges that can capture such features. First, the dynamic stress range response of the bridge is obtained from the coupled train–track–bridge system. Then, the stress range is modeled as a continuous nonstationary stochastic process based on its stochastic characteristics throughout the bridge design life. To describe its probabilistic characteristics, a moment-based method is employed, enabling a flexible representation of its marginal distribution and autocorrelation function. Finally, the method is applied to analyze the stress range of an actual railway steel bridge, demonstrating its practical applicability. It is found in this study that the marginal distribution of the stress range can be approximated as a cubic normal distribution with good accuracy, and that the autocorrelation function indicates the clear time dependency of the stress range. A merit of the proposed method is that it can capture the temporal and random characteristics of dynamic loads on steel bridges. The contribution of this study is the provision of good guidance for engineers and asset managers in the assessment and management of heavy-haul railway bridges under fatigue loads.
Transient Response Characterization of Wind Turbine Structure–Extended Foundation Under Wind Loading
Authors: Fan Zi-Jian , Liu Xin-Xi , Deng Zong-Wei , Liu Wen-Jie , Men Sheng-Ming , Li Yu
Published: January 2025

To study the transient response characteristics of wind turbine structures–extended foundations under wind loads in mountainous areas, this paper develops a simplified analytical model based on soil–structure interaction theory. It explores the effects of constraint conditions, wind speed, and foundation shear wave speed on the transient response behavior. By analyzing the time–domain and frequency–domain trends of tower top displacement, foundation horizontal displacement, and foundation rotation angle, the relationship between foundation shear wave speed and the safe wind speed of the wind turbine is clarified. The results indicate that different constraint conditions lead to variations in the calculated resonance frequency, maximum tower top displacement, and acceleration response spectrum. Furthermore, based on the analysis of the tower top acceleration response curve, the influence interval of frequency can be categorized into three distinct ranges: stable range, small influence range, and large influence range. Wind speed primarily influences the vibration amplitudes of the three displacement components, while the overall trend of the time-displacement waveform remains unchanged. The foundation shear wave speed primarily affects the displacement of the foundation itself, exerting a smaller influence on the displacements of the wind turbine structure. Notably, the total displacement at the tower top decreases as the shear wave speed increases. Moreover, the safe wind speed of the wind turbine shows a positive correlation with the foundation shear wave speed, indicating a linear relationship between the two variables.
Buckling of Simply Supported Bi-Periodic Elastic Columns
Authors: Elishakoff Isaac , Challamel Noël , Keita Lassiné , Picandet Vincent
Published: January 2025

In this paper, the buckling of a simply supported stepped periodic column is studied using an analytical method. The column is composed of biperiodic cells of stepped Euler–Bernoulli continuous segments. The deflection solution in each cell can be expressed from the resolution of a fourth-order differential equation. After expressing the continuity conditions between each cell, it is possible to relate the solution of each cell with respect to its neighbors. The differential eigenvalue problem of the bi-periodic structure is converted into a linear difference eigenvalue problem associated to the coefficients of the expressed solution in each cell. A transcendental equation for the buckling load of the continuous biperiodic column is obtained from the resolution of the discrete linear difference eigenvalue problem. This transcendental equation is valid whatever the number [Formula: see text] of bi-periodic cells, with [Formula: see text] larger than 2. This general expression is corroborated with the buckling values obtained using a direct method for few cells ([Formula: see text] and [Formula: see text] for instance). The behavior of the stability limit for large [Formula: see text] values is also specifically studied. It is shown that the bi-periodic column asymptotically converges toward a homogenized Euler–Bernoulli column with equivalent stiffness calibrated from Reuss’s averaging method. More refined beam models are also derived using asymptotic arguments. The buckling load converges toward the one of a gradient beam model for sufficiently large number [Formula: see text] of cells, which can be equivalently derived from a second-order homogenized beam theory. The convergence of this second-order homogenized beam model toward the equivalent homogenized Euler–Bernoulli column (obtained from Reuss’s averaging method) is from below, as also reported for the exact solution of the biperiodic continuous column. A comparison is also carried out for large values of [Formula: see text] with a nonlocal Euler–Bernoulli model, which has the same order of accuracy as obtained from the gradient beam model (second-order homogenized beam model).
Coupling Mechanism and Compensation Control Method for a Frequency Bandwidth Expansion Compound Shaking Table
Authors: Liang Jianwen , Ding Zhen , Han Qinghua , Wu Hao , Lu Yan , Liu Mingjie , Ji Jinbao
Published: January 2025

The frequency bandwidth expansion compound shaking table (FBECST) provides an effective solution for synchronously achieving large-load, long-stroke, and wide-band excitation. FBECST consists of an upper shaking table (UST) and a lower shaking table (LST) cooperating to realize the compound excitation, which results in a high system complexity compared to the traditional shaking table. However, the coupling mechanism and model-based compensation control method of FBECST have rarely been studied, which greatly limits the ability of FBECST to simulate earthquake excitation. In this paper, a closed-loop transfer function matrix theoretical model of FBECST is developed. Then, the coupling mechanism of FBECST is revealed by theoretical analysis, and the correctness of the mechanism analysis is verified by simulation. Finally, a closed-loop feedforward decoupling compensation control (C-FDCC) method based on the coupling mechanism of FBECST is proposed. A series of numerical analysis results show that even considering the influence of a high natural frequency specimen, the proposed C-FDCC method can achieve good control precision with a time-domain correlation coefficient near 0.98, whereas the three-variable control(TVC) provides insufficient control. This work provides strong support for large-load, long-stroke, and wide-band seismic excitation reproduction through the FBECST.
Dao numbers and the asymptotic Behavior of fullness
Authors: Ficarra Antonino
Published: January 2025

In this paper, we study the Dao numbers [Formula: see text] and [Formula: see text] of an ideal [Formula: see text] of a Noetherian local ring [Formula: see text] or a standard graded Noetherian [Formula: see text]-algebra. They are defined as the smallest [Formula: see text] such that [Formula: see text] is [Formula: see text]-full, full, weakly [Formula: see text]-full, respectively, for all [Formula: see text]. We provide general bounds for the Dao numbers in terms of the Castelnuovo–Mumford regularity of certain modules over the Rees algebra [Formula: see text]. If [Formula: see text] is a Koszul algebra, we prove that the Dao numbers are less or equal to [Formula: see text], where [Formula: see text] is the associated graded module of [Formula: see text]. Finally, for monomial ideals, we combinatorially bound the Dao numbers in terms of asymptotic linear quotients and bounding multidegrees.
On the strongly irreducible ideals of a duo ring
Authors: Hashemi Jamal , Yari Hossein
Published: January 2025

A proper ideal [Formula: see text] in a ring [Formula: see text] is called strongly irreducible (briefly, SI-ideal), if [Formula: see text] then [Formula: see text] or [Formula: see text], where [Formula: see text], [Formula: see text] are ideals of [Formula: see text]. We show that whenever in a local Noetherian duo domain, a power of its maximal ideal, [Formula: see text] say, is principal, then so is [Formula: see text]. It is also shown that whenever [Formula: see text] is an SI-ideal in a Noetherian duo ring [Formula: see text] where [Formula: see text] and [Formula: see text] with [Formula: see text], then [Formula: see text] is a domain. Finally in a Noetherian duo ring [Formula: see text], non-prime ideals with positive heights, which are SI-ideal, are characterized.
Orbits of unipotent elements in the generalized symmetric space defined by inner involutions of SL3(𝔽q) and SL4(𝔽q) for q = 2n
Authors: Buell C. , Helminck A. , Klima V. , Schaefer J. , Wright C. , Ziliak E.
Published: January 2025

In this paper, we characterize and classify the orbits of the fixed-point group on the unipotent elements of the generalized symmetric spaces for inner involutions of [Formula: see text] and [Formula: see text] where [Formula: see text] is a finite field of even characteristic. We also provide some generalized results for [Formula: see text]. These results, together with our previous work that determined similar orbits when [Formula: see text] is a finite field of odd characteristic, complete the classification of the orbits of the fixed-point group on the unipotent elements of the generalized symmetric spaces for inner involutions of [Formula: see text] and [Formula: see text] for any finite field [Formula: see text] of any characteristic.
Geometry of umbrella matrices in Galilean space
Authors: Çarboğa M. , Yaylı Y.
Published: January 2025

In this study, we examine the Umbrella matrix group in Galilean space, which possesses the stochastic matrix property (i.e. leaves the [Formula: see text] axis fixed) within matrix groups. In our examination, we first obtain the matrix Lie group and Lie algebra in [Formula: see text] space and then generalize this result. Furthermore, we present the Cayley formula, which gives the transition between the [Formula: see text] Lie group and Lie algebra, for the first time between the Galilean Umbrella matrix Lie group and Lie algebra. Then, we define a case of shear motion along the [Formula: see text] axis with the help of a special Galilean transformation and generate rotated surfaces in Galilean space using certain curves.
Exact soliton solutions for the (n + 1)-dimensional generalized Kadomtsev–Petviashvili equation via two novel methods
Authors: Kopçasız Bahadır , Sağlam Fatma Nur Kaya , Malik Sandeep
Published: January 2025

In this study, we deal with the [Formula: see text]-dimensional generalized Kadomtsev–Petviashvili equation (gKPE). This equation is an extension of the classical KP equation to higher dimensions, allowing for the study of nonlinear wave propagation in [Formula: see text] dimensions. Like the original KP equation, the [Formula: see text]-dimensional version can support soliton solutions, which are stable waveforms that retain their shape while traveling. The [Formula: see text]-dimensional gKPE has several applications in different physical systems, such as optical fibers, Bose–Einstein condensates, fluid physics, and plasma physics. We use two efficient methods to search for analytical solutions to the equation we consider. One of these methods is the generalized unified method and the improved [Formula: see text]-expansion method. Using these techniques, we obtain many soliton solutions of rational, hyperbolic, and trigonometric types. We present 3D, contour, and density plots to observe the behavior of some of the solutions we obtained. The acquired results constitute an essential resource for the study of hydrodynamic waves, plasma fluctuations, and optical solitons and offer useful information for understanding the behavior of the KPE under different physical situations. The methodologies used in this study are robust, influential, and practicable for diverse nonlinear partial differential equations; to our knowledge, these methods of investigation have not been explored before for this equation. The accuracy of each solution has been verified using the Maple software program.
Maximal Simplification of Polyhedral Reductions
Authors: Narmour Louis , Yuki Tomofumi , Rajopadhye Sanjay
Published: January 2025

Reductions combine collections of input values with an associative and often commutative operator to produce collections of results. When the same input value contributes to multiple outputs, there is an opportunity to reuse partial results, enabling reduction simplification. Simplification often produces a program with lower asymptotic complexity. Typical compiler optimizations yield, at best, a constant fold speedup, but a complexity improvement from, say, cubic to quadratic complexity yields unbounded speedup for sufficiently large problems. It is well known that reductions in polyhedral programs may be simplified automatically, but previous methods cannot exploit all available reuse. This paper resolves this long-standing open problem, thereby attaining minimal asymptotic complexity in the simplified program. We propose extensions to prior work on simplification to support any independent commutative reduction. At the heart of our approach is piece-wise simplification, the notion that we can split an arbitrary reduction into pieces and then independently simplify each piece. However, the difficulty of using such piece-wise transformations is that they typically involve an infinite number of choices. We give constructive proofs to deal with this and select a finite number of pieces for simplification.
The Duality of λ-Abstraction
Authors: Choudhury Vikraman , Gay Simon J.
Published: January 2025

In this paper, we develop and study the following perspective -- just as higher-order functions give exponentials, higher-order continuations give coexponentials. From this, we design a language that combines exponentials and coexponentials, producing a duality of lambda abstraction.

We formalise this language by giving an extension of a call-by-value simply-typed lambda-calculus with covalues, coabstraction, and coapplication. We develop the semantics of this language using the axiomatic structure of continuations, which we use to produce an equational theory, that gives a complete axiomatisation of control effects. We give a computational interpretation to this language using speculative execution and backtracking, and use this to derive the classical control operators and computational interpretation of classical logic, and encode common patterns of control flow using continuations. By dualising functional completeness, we further develop duals of first-order arrow languages using coexponentials. Finally, we discuss the implementation of this duality as control operators in programming, and develop some applications.
A Dependent Type Theory for Meta-programming with Intensional Analysis
Authors: Hu Jason Z. S. , Pientka Brigitte
Published: January 2025

In this paper, we introduce DeLaM, a dependent layered modal type theory which enables meta-programming in Martin-Löf type theory (MLTT) with recursion principles on open code. DeLaM includes three layers: the layer of static syntax objects of MLTT without any computation; the layer of pure MLTT with the computational behaviors; the meta-programming layer extends MLTT with support for quoting an open MLTT code object and composing and analyzing open code using recursion. We can also execute a code object at the meta-programming layer. The expressive power strictly increases as we move up in a given layer. In particular, while code objects only describe static syntax, we allow computation at the MLTT and meta-programming layer. As a result, DeLaM provides a dependently typed foundation for meta-programming that supports both type-safe code generation and code analysis. We prove the weak normalization of DeLaM and the decidability of convertibility using Kripke logical relations.
Axe ’Em: Eliminating Spurious States with Induction Axioms
Authors: Elad Neta , Shoham Sharon
Published: January 2025

First-order logic has proved to be a versatile and expressive tool as the basis of abstract modeling

languages. Used to verify complex systems with unbounded domains, such as heap-manipulating

programs and distributed protocols, first-order logic, and specifically uninterpreted functions and

quantifiers, strike a balance between expressiveness and amenity to automation. However, first-order logic semantics may differ in important ways from the intended semantics of the modeled

system, due to the inability to distinguish between finite and infinite first-order structures, for

example, or the undefinability of well-founded relations in first-order logic. This semantic gap may

give rise to spurious states and unreal behaviors, which only exist as an artifact of the first-order abstraction and impede the verification process.

In this paper we take a step towards bridging this semantic gap. We present an approach for

soundly refining the first-order abstraction according to either well-founded semantics or finite-domain semantics, utilizing induction axioms for an abstract order relation, a common primitive in

verification. We first formalize sound axiom schemata for each of the aforementioned semantics,

based on well-founded induction. Second, we show how to use spurious counter-models, which

are necessarily infinite, to guide the instantiation of these axiom schemata. Finally, we present a

sound and complete reduction of well-founded semantics and finite-domain semantics to standard

semantics in the recently discovered Ordered Self-Cycle (OSC) fragment of first-order logic, and

prove that satisfiability under these semantics is decidable in OSC.

We implement a prototype tool to evaluate our approach, and test it on various examples where

spurious models arise, from the domains of distributed protocols and heap-manipulating programs.

Our tool quickly finds the necessary axioms to refine the semantics, and successfully completes the

verification process, eliminating the spurious system states that blocked progress.
Formal Foundations for Translational Separation Logic Verifiers
Authors: Dardinier Thibault , Sammler Michael , Parthasarathy Gaurav , Summers Alexander J. , Müller Peter
Published: January 2025

Program verification tools are often implemented as front-end translations of an input program into an intermediate verification language (IVL) such as Boogie, GIL, Viper, or Why3. The resulting IVL program is then verified using an existing back-end verifier. A soundness proof for such a translational verifier needs to relate the input program and verification logic to the semantics of the IVL, which in turn needs to be connected with the verification logic implemented in the back-end verifiers. Performing such proofs is challenging due to the large semantic gap between the input and output programs and logics, especially for complex verification logics such as separation logic.

This paper presents a formal framework for reasoning about translational separation logic verifiers. At its center is a generic core IVL that captures the essence of different separation logics. We define its operational semantics and formally connect it to two different back-end verifiers, which use symbolic execution and verification condition generation, resp. Crucially, this semantics uses angelic non-determinism to enable the application of different proof search algorithms and heuristics in the back-end verifiers. An axiomatic semantics for the core IVL simplifies reasoning about the front-end translation by performing essential proof steps once and for all in the equivalence proof with the operational semantics rather than for each concrete front-end translation.

We illustrate the usefulness of our formal framework by instantiating our core IVL with elements of Viper and connecting it to two Viper back-ends as well as a front-end for concurrent separation logic. All our technical results have been formalized in Isabelle/HOL, including the core IVL and its semantics, the semantics of two back-ends for a subset of Viper, and all proofs.
Progressful Interpreters for Efficient WebAssembly Mechanisation
Authors: Rao Xiaojia , Radziuk Stefan , Watt Conrad , Gardner Philippa
Published: January 2025

Mechanisations of programming language specifications are now increasingly common, providing machine-checked modelling of the specification and verification of desired properties such as type safety. However it is challenging to maintain these mechanisations, particularly in the face of an evolving specification. Existing mechanisations of the W3C WebAssembly (Wasm) standard have so far been able to keep pace as the standard evolves, helped enormously by the W3C Wasm standard's choice to state the language's semantics in terms of a fully formal specification. However a substantial incoming extension to Wasm, the 2.0 feature set, motivates the investigation of strategies for more efficient production of the core verification artefacts currently associated with the WasmCert-Coq mechanisation of Wasm.

In the classic formalisation of a typed operational semantics as followed by the W3C Wasm standard, both the type system and runtime operational semantics are defined as inductive relations, with associated type soundness properties (progress and preservation) and an independent sound interpreter. We investigate two more efficient strategies for producing these artefacts, which are currently all separately defined by WasmCert-Coq. First, the approach of Kokke, Siek, and Wadler for deriving a sound interpreter from a constructive progress proof --- we show that this approach scales to the W3C Wasm 1.0 standard, but results in an inefficient interpreter in our setting. Second, inspired by results from intrinsically-typed languages, we define a progressful interpreter which uses Coq's dependent types to certify not only its own soundness, but also the progress property. We show that this interpreter can implement several performance optimisations while maintaining these certifications, which are fully erasable when the interpreter is extracted from Coq. Using this approach, we extend the WasmCert-Coq mechanisation to the significantly larger Wasm 2.0 feature set, discovering and correcting several errors in the expanded specification's type system.
A Verified Foreign Function Interface between Coq and C
Authors: Korkut Joomy , Stark Kathrin , Appel Andrew W.
Published: January 2025

One can write dependently typed functional programs in Coq, and prove

them correct in Coq; one can write low-level programs in C, and prove them

correct with a C verification tool. We demonstrate how to write programs

partly in Coq and partly in C, and interface the proofs together. The Verified Foreign Function Interface (VeriFFI) guarantees type safety and correctness

of the combined program. It works by translating Coq function types

(and constructor types) along with Coq functional models into VST

function-specifications; if the user can prove in VST that the C functions

satisfy those specs, then the C functions behave according to the

user-specified functional models (even though the C implementation

might be very different) and the proofs of Coq functions that call the C code

can rely on that behavior. To achieve this translation, we employ

a novel, hybrid deep/shallow description of Coq dependent types.
Simple Linear Loops: Algebraic Invariants and Applications
Authors: Ait El Manssour Rida , Kenison George , Shirmohammadi Mahsa , Varonka Anton
Published: January 2025

The automatic generation of loop invariants is a fundamental challenge in software verification. While this task is undecidable in general, it is decidable for certain restricted classes of programs. This work focuses on invariant generation for (branching-free) loops with a single linear update.

Our primary contribution is a polynomial-space algorithm that computes the strongest algebraic invariant for simple linear loops, generating all polynomial equations that hold among program variables across all reachable states. The key to achieving our complexity bounds lies in mitigating the blow-up associated with variable elimination and Gröbner basis computation, as seen in prior works. Our procedure runs in polynomial time when the number of program variables is fixed.

We examine various applications of our results on invariant generation, focusing on invariant verification and loop synthesis. The invariant verification problem investigates whether a polynomial ideal defining an algebraic set serves as an invariant for a given linear loop. We show that this problem is coNP-complete and lies in PSPACE when the input ideal is given in dense or sparse representations, respectively. In the context of loop synthesis, we aim to construct a loop with an infinite set of reachable states that upholds a specified algebraic property as an invariant. The strong synthesis variant of this problem requires the construction of loops for which the given property is the strongest invariant. In terms of hardness, synthesising loops over integers (or rationals) is as hard as Hilbert's Tenth problem (or its analogue over the rationals). When the constants of the output are constrained to bit-bounded rational numbers, we demonstrate that loop synthesis and its strong variant are both decidable in PSPACE, and in NP when the number of program variables is fixed.
Denotational Semantics of Gradual Typing using Synthetic Guarded Domain Theory
Authors: Giovannini Eric , Ding Tingting , New Max S.
Published: January 2025

Gradually typed programming languages, which allow for soundly

mixing static and dynamically typed programming styles, present a

strong challenge for metatheorists. Even the simplest sound

gradually typed languages feature at least recursion and errors,

with realistic languages featuring furthermore runtime allocation of

memory locations and dynamic type tags. Further, the desired

metatheoretic properties of gradually typed languages have become

increasingly sophisticated: validity of type-based equational

reasoning as well as the relational property known as

graduality. Many recent works have tackled verifying these

properties, but the resulting mathematical developments are highly

repetitive and tedious, with few reusable theorems persisting across

different developments.

In this work, we present a new denotational semantics for gradual

typing developed using guarded domain theory. Guarded domain theory

combines the generality of step-indexed logical relations for

modeling advanced programming features with the modularity and

reusability of denotational semantics. We demonstrate the

feasibility of this approach with a model of a simple gradually

typed lambda calculus and prove the validity of beta-eta equality

and the graduality theorem for the denotational model. This model

should provide the basis for a reusable mathematical theory of

gradually typed program semantics. Finally, we have mechanized most

of the core theorems of our development in Guarded Cubical Agda, a

recent extension of Agda with support for the guarded recursive

constructions we use.
Guaranteed Bounds on Posterior Distributions of Discrete Probabilistic Programs with Loops
Authors: Zaiser Fabian , Murawski Andrzej S. , Ong C.-H. Luke
Published: January 2025

We study the problem of bounding the posterior distribution of discrete probabilistic programs with unbounded support, loops, and conditioning. Loops pose the main difficulty in this setting: even if exact Bayesian inference is possible, the state of the art requires user-provided loop invariant templates. By contrast, we aim to find
guaranteed bounds
, which sandwich the true distribution. They are fully automated, applicable to more programs and provide more provable guarantees than approximate sampling-based inference. Since lower bounds can be obtained by unrolling loops, the main challenge is upper bounds, and we attack it in two ways. The first is called
residual mass semantics
, which is a flat bound based on the residual probability mass of a loop. The approach is simple, efficient, and has provable guarantees.

The main novelty of our work is the second approach, called
geometric bound semantics
. It operates on a novel family of distributions, called
eventually geometric distributions
(EGDs), and can bound the distribution of loops with a new form of loop invariants called
contraction invariants
. The invariant synthesis problem reduces to a system of polynomial inequality constraints, which is a decidable problem with automated solvers. If a solution exists, it yields an exponentially decreasing bound on the
whole
distribution, and can therefore bound moments and tail asymptotics as well, not just probabilities as in the first approach.

Both semantics enjoy desirable theoretical properties. In particular, we prove soundness and convergence, i.e. the bounds converge to the exact posterior as loops are unrolled further. We also investigate sufficient and necessary conditions for the existence of geometric bounds. On the practical side, we describe
Diabolo
, a fully-automated implementation of both semantics, and evaluate them on a variety of benchmarks from the literature, demonstrating their general applicability and the utility of the resulting bounds.
Preservation of Speculative Constant-Time by Compilation
Authors: Arranz Olmos Santiago , Barthe Gilles , Blatter Lionel , Grégoire Benjamin , Laporte Vincent
Published: January 2025

Compilers often weaken or even discard software-based countermeasures commonly used to protect programs against side-channel attacks; worse, they may also introduce vulnerabilities that attackers can exploit. The solution to this problem is to develop compilers that preserve such countermeasures. Prior work establishes that (a mildly modified version of) the CompCert and Jasmin formally verified compilers preserve constant-time, an information flow policy that ensures that programs are protected against timing side-channel attacks. However, nothing is known about preservation of speculative constant-time, a strengthening of the constant-time policy that ensures that programs are protected against Spectre-v1 attacks. We first show that preservation of speculative constant-time fails in practice by providing examples of secure programs whose compilation is not speculative constant-time using GCC (GCC -O0 and GCC -O1) and Jasmin. Then, we define a proof-of-concept compiler that distills some of the critical passes of the Jasmin compiler and use the Coq proof assistant to prove that it preserves speculative constant-time. Finally, we patch the Jasmin speculative constant-time type checker and demonstrate that all cryptographic implementations written in Jasmin can be fixed with minimal impact.
Compositional Imprecise Probability: A Solution from Graded Monads and Markov Categories
Authors: Liell-Cock Jack , Staton Sam
Published: January 2025

Imprecise probability is concerned with uncertainty about which probability distributions to use. It has applications in robust statistics and machine learning.

We look at programming language models for imprecise probability. Our desiderata are that we would like our model to support all kinds of composition, categorical and monoidal; in other words, guided by dataflow diagrams. Another equivalent perspective is that we would like a model of synthetic probability in the sense of Markov categories.

Imprecise probability can be modelled in various ways, with the leading monad-based approach using convex sets of probability distributions. This model is not fully compositional because the monad involved is not commutative, meaning it does not have a proper monoidal structure. In this work, we provide a new fully compositional account. The key idea is to name the non-deterministic choices. To manage the renamings and disjointness of names, we use graded monads. We show that the resulting compositional model is maximal and relate it with the earlier monadic approach, proving that we obtain tighter bounds on the uncertainty.
Unifying Compositional Verification and Certified Compilation with a Three-Dimensional Refinement Algebra
Authors: Zhang Yu , Koenig Jérémie , Shao Zhong , Wang Yuting
Published: January 2025

Formal verification is a gold standard for building reliable computer systems. Certified systems in particular come with a formal specification, and a proof of correctness which can easily be checked by a third party.

Unfortunately, verifying large-scale, heterogeneous systems remains out of reach of current techniques. Addressing this challenge will require the use of compositional methods capable of accommodating and interfacing a range of program verification and certified compilation techniques. In principle, compositional semantics could play a role in enabling this kind of flexibility, but in practice existing tools tend to rely on simple and specialized operational models which are difficult to interface with one another.

To tackle this issue, we present a compositional semantics framework which can accommodate a broad range of verification techniques. Its core is a three-dimensional algebra of refinement which operates across program modules, levels of abstraction, and components of the system's state. Our framework is mechanized in the Coq proof assistant and we showcase its capabilities with multiple use cases.