Can Large Language Models Write Good Property-Based Tests?

Property-based testing (PBT), while an established technique in the software testing research community, is still relatively underused in real-world software. Pain points in writing property-based tests include implementing diverse random input generators and thinking of meaningful properties to test. Developers, however, are more amenable to writing documentation; plenty of library API documentation is available and can be used as natural language specifications for property-based tests. As large language models (LLMs) have recently shown promise in a variety of coding tasks, we explore the potential of using LLMs to synthesize property-based tests. We call our approach PBT-GPT, and propose three different strategies of prompting the LLM for PBT. We characterize various failure modes of PBT-GPT and detail an evaluation methodology for automatically synthesized property-based tests. PBT-GPT achieves promising results in our preliminary studies on sample Python library APIs in $\texttt{numpy}$, $\texttt{networkx}$, and $\texttt{datetime}$

Caractérisation de l'homologue de PABPN1 (Poly(A)-Binding Protein Nuclear 1) chez la levure à fission Schizosaccharomyces pombe

Deux classes de poly(A)-binding protein (PABP) lient la queue poly(A) des ARNm chez la plupart des mammifères: PABPC1 au cytosol et PABPN1 au noyau. PABPC1 stimule la traduction des ARNm tandis que PABPN1 stimule la processivité de la poly(A) polymérase tout en contrôlant la taille des queues poly(A). Il est à noter que les orthologues de PABPC1 sont bien caractérisés chez la levure, toutefois un homologue de PABPN1 n'avait jamais été identifié. Précédemment, le Dr. Bachand avait réalisé une purification par affinité avec la protéine d’arginine méthyltransférase I (Rmt1) couplée à la spectrométrie de masse, ce qui a permis d'identifier l’homologue de PABPN1 (Pab2) chez la levure à fission. Différentes expériences ont démontré que Pab2 est une protéine nucléaire non-essentielle qui lie spécifiquement des séquences poly(A) in vitro. Pab2 a été identifiée par son interaction avec Rmt1 et cette enzyme méthyle les arginines présentes dans le domaine riche en arginine de la protéine Pab2. Cette modification post-traductionnelle n'affecte pas la localisation nucléaire et l’affinité aux séquences poly(A) de Pab2. Par contre, les niveaux d’oligomérisation de Pab2 sont nettement augmentés lorsque Pab2 n’est plus méthylée. De plus, les ARNs provenant de cellules [Delta]pab2 sont hyperadénylés, ce qui corrobore avec la fonction de PABPN1 à contrôler la taille des queues poly(A) in vitro. Par la suite, j'ai caractérisé l’implication de Pab2 durant la maturation du pré-ARNm. Des essais d'immunoprécipitation de chromatine (ChIP) ont établi que Pab2 est recrutée co-transcriptionnellement aux gènes activement transcrits. De façon surprenante, mes études ont démontré que le recrutement de Pab2 précède celui d'un facteur impliqué dans le clivage et la polyadénylation. De plus, le recrutement de Pab2 dépend de l’ARNm naissant. Conséquemment, j'ai voulu identifier les protéines associées à Pab2. Ainsi, une purification d’affinité par tandem couplée à la spectrométrie de masse a révélé que Pab2 est associée à plusieurs protéines ribosomales ainsi que des facteurs de traduction générale. Ces données étaient étonnantes puisque la traduction des ARNm implique la protéine Pab1. Par conséquent, il était pertinent de vérifier le rôle possible de Pab2 sur la traduction. À priori, j ’ai confirmé que Pab2 fait la navette entre le noyau et le cytosol, ce qui concorde avec l’orthologue PABPN1. Par la suite, j'ai démontré qu’une fraction de la protéine Pab2 demeure associée aux ARNm activement traduits. Il devenait alors intéressant de connaître les cibles de Pab2. L’analyse génomique a établi que Pab2 régule l’expression de certains transcrits, tels que les gènes méïotiques, les snoRNAs et les rétrotransposons. Pour la suite de mes recherches, je me suis concentrée sur le gène codant pour la protéine ribosomale de la large sous-unité Rpl30-2, dont l’expression augmente de 4 fois en absence de Pab2. Il est intéressant de noter que le changement d ’expression de Rpl30-2 dans une souche [Delta]pab2 dépend de la présence de l’intron Rpl30-2. Mes travaux démontrent que l’expression de Rpl30-2 est régulée au niveau du pré-ARNm par Pab2 et Rrp6, une composante de l’exosome nucléaire. De plus, l’analyse du transcriptome par RNA-seq a établi que ce mécanisme permet de réguler l’expression d'une soixantaine de gènes qui sont inefficacement épissés. En ce qui concerne Rpl30-2, l’épissage de ce transcrit est ralenti par Rpl30-1, le paralogue de Rpl30-2. L’ensemble de mes travaux ont pu caractériser l’homologue de PABPN1 (Pab2) chez la levure à fission tout en établissant une fonction spécifique pour cette poly(A)-binding protein

Activités proinflammatoires des angiopoïétines

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Les cellules de la moelle osseuse : une cible réelle des estrogènes dans la protection cardiovasculaire?

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Cartographie et classification du terrain à potentiel avalancheux des Chics-Chocs, Québec, Canada, à l'aide d'un système d'information géographique

Avalanche sites mapping and classification are tools that have been frequently used for managing avalanche risks. The use of geographic information systems (GIS) for such applications has great potential although it is still in development. The potential avalanche sites of the Chic-Chocs Mountains, Québec, Canada, was mapped with GIS technology, satellite images, aerial photos and 1:20 000 topographic maps. A forest map, including three different levels of forest density, was generated from the satellite image. A total of 59 zones composed of 249 sub-zones and paths, were localized and characterised by 16 attributes. Moreover, in order to build the institutional memory bank of one of the most frequented area by winter sports adepts in Québec, a system was created to allow future cataloguing of avalanche occurrences inside the potential avalanche location map. The database, currently having 48 events dated between 1987 and 2006, linked to a GIS allows the visualisation of the spatial distribution of avalanche occurrences and is the basis for the study of potential correlation topographic parameters and weather patterns. Another terrain analysis was also performed to address the challenge of the access restrictions of Mount-Albert in Gaspésie National Park. A terrain classification by exposure to avalanches based on Parks Canada's technical model was performed in order to help safer management of the park's winter activities. The results show that in surface, 41% of the terrain analysed has a high degree of exposition to avalanches. An English version of this thesis is summarized in annex 7

Mixing Low-Precision Formats in Multiply-Accumulate Units for DNN Training

International audienceThe most compute-intensive stage of deep neural network (DNN) training is matrix multiplication where the multiply-accumulate (MAC) operator is key. To reduce training costs, we consider using low-precision arithmetic for MAC operations. While low-precision training has been investigated in prior work, the focus has been on reducing the number of bits in weights or activations without compromising accuracy. In contrast, the focus in this paper is on implementation details beyond weight or activation width that affect area and accuracy. In particular, we investigate the impact of fixed-versus floating-point representations, multiplier rounding, and floatingpoint exceptional value support. Results suggest that (1) lowprecision floating-point is more area-effective than fixed-point for multiplication, (2) standard IEEE-754 rules for subnormals, NaNs, and intermediate rounding serve little to no value in terms of accuracy but contribute significantly to area, (3) lowprecision MACs require an adaptive loss-scaling step during training to compensate for limited representation range, and (4) fixed-point is more area-effective for accumulation, but the cost of format conversion and downstream logic can swamp the savings. Finally, we note that future work should investigate accumulation structures beyond the MAC level to achieve further gains

Validity fuzzing and parametric generators for effective random testing

peer reviewe

Cupid: Automatic Fuzzer Selection for Collaborative Fuzzing

Combining the strengths of individual fuzzing methods is an appealing idea to find software faults more efficiently, especially when the computing budget is limited. In prior work, EnFuzz introduced the idea of ensemble fuzzing and devised three heuristics to classify properties of fuzzers in terms of diversity. Based on these heuristics, the authors manually picked a combination of different fuzzers that collaborate. In this paper, we generalize this idea by collecting and applying empirical data from single, isolated fuzzer runs to automatically identify a set of fuzzers that complement each other when executed collaboratively. To this end, we present Cupid, a collaborative fuzzing framework allowing automated, data-driven selection of multiple complementary fuzzers for parallelized and distributed fuzzing. We evaluate the automatically selected target-independent combination of fuzzers by Cupid on Google's fuzzer-test-suite, a collection of real-world binaries, as well as on the synthetic Lava-M dataset. We find that Cupid outperforms two expert-guided, target-specific and hand-picked combinations on Google's fuzzer-test-suite in terms of branch coverage, and improves bug finding on Lava-M by 10%. Most importantly, we improve the latency for obtaining 95% and 99% of the coverage by 90% and 64%, respectively. Furthermore, Cupid reduces the amount of CPU hours needed to find a high-performing combination of fuzzers by multiple orders of magnitude compared to an exhaustive evaluation

Mapping preictal and ictal haemodynamic networks using video-electroencephalography and functional imaging

Ictal patterns on scalp-electroencephalography are often visible only after propagation, therefore rendering localization of the seizure onset zone challenging. We hypothesized that mapping haemodynamic changes before and during seizures using simultaneous video-electroencephalography and functional imaging will improve the localization of the seizure onset zone. Fifty-five patients with ≥2 refractory focal seizures/day, and who had undergone long-term video-electroencephalography monitoring were included in the study. ‘Preictal' (30 s immediately preceding the electrographic seizure onset) and ictal phases, ‘ictal-onset'; ‘ictalestablished' and ‘late ictal', were defined based on the evolution of the electrographic pattern and clinical semiology. The functional imaging data were analysed using statistical parametric mapping to map ictal phase-related haemodynamic changes consistent across seizures. The resulting haemodynamic maps were overlaid on co-registered anatomical scans, and the spatial concordance with the presumed and invasively defined seizure onset zone was determined. Twenty patients had typical seizures during functional imaging. Seizures were identified on video-electroencephalography in 15 of 20, on electroencephalography alone in two and on video alone in three patients. All patients showed significant ictal-related haemodynamic changes. In the six cases that underwent invasive evaluation, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure onset zone for all patients. The most statistically significant haemodynamic cluster within the presumed seizure onset zone was between 1.1 and 3.5 cm from the invasively defined seizure onset zone, which was resected in two of three patients undergoing surgery (Class I post-surgical outcome) and was not resected in one patient (Class III post-surgical outcome). In the remaining 14 cases, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure onset zone in six of eight patients with structural-lesions and five of six non-lesional patients. The most statistically significant haemodynamic cluster was localizable at sub-lobar level within the presumed seizure onset zone in six patients. The degree of concordance of haemodynamic maps was significantly better (P < 0.05) for the ictal-onset phase [entirely concordant/concordant plus (13/20; 65%) + some concordance (4/20; 20%) = 17/20; 85%] than ictal-established [entirely concordant/concordant plus (5/13; 38%) + some concordance (4/13; 31%) = 9/13; 69%] and late ictal [concordant plus (1/9; 11%) + some concordance (4/9; 44%) = 5/9; 55%] phases. Ictal propagation-related haemodynamic changes were also seen in symptomatogenic areas (9/20; 45%) and the default mode network (13/20; 65%). A common pattern of preictal changes was seen in 15 patients, starting between 98 and 14 s before electrographic seizure onset, and the maps had a degree of concordance with the presumed seizure onset zone in 10 patients. In conclusion, preictal and ictal haemodynamic changes in refractory focal seizures can non-invasively localize seizure onset at sub-lobar/gyral level when ictal scalp-electroencephalography is not helpfu