Using genetic programming to evolve action selection rules in traversal-based automated software testing: results obtained with the TESTAR tool

Traversal-based automated software testing involves testing an application via its graphical user interface (GUI) and thereby taking the user’s point of view and executing actions in a human-like manner. These actions are decided on the fly, as the software under test (SUT) is being run, as opposed to being set up in the form of a sequence prior to the testing, a sequence that is then used to exercise the SUT. In practice, random choice is commonly used to decide which action to execute at each state (a procedure commonly referred to as monkey testing), but a number of alternative mechanisms have also been proposed in the literature. Here we propose using genetic programming (GP) to evolve such an action selection strategy, defined as a list of IF-THEN rules. Genetic programming has proved to be suited for evolving all sorts of programs, and rules in particular, provided adequate primitives (functions and terminals) are defined. These primitives must aim to extract the most relevant information from the SUT and the dynamics of the testing process. We introduce a number of such primitives suited to the problem at hand and evaluate their usefulness based on various metrics. We carry out experiments and compare the results with those obtained by random selection and also by Q-learning, a reinforcement learning technique. Three applications are used as Software Under Test (SUT) in the experiments. The analysis shows the potential of GP to evolve action selection strategies.     

Melting behavior in blends of isotactic polypropylene and a liquid crystalline polymer

The influence of low contents of a liquid crystalline polymer on the crystallization and melting behavior of isotactic polypropylene (iPP) was investigated using electron and optical microscopy, differential scanning calorimetry, and X-ray diffraction. In pure iPP, the α modification was found, whereas for iPP/Vectra blends at Vectra concentration <5%, both α and β forms were observed. The amount of β phase varied from 0.23 to 0.16. Optical microscopy showed that Vectra was able to nucleate both α and β forms. Non-isothermal crystallization produces a material with a strong tendency for recrystallization of the α and β forms (αα′ and ββ′ recrystallization) leading to double endotherms for both crystalline forms in DSC thermograms. Melting thermograms after isothermal crystallization at low temperatures showed a similar behavior. At values of T_c > 119 °C for the α form and T_c > 125 °C for the β form, only one melting endotherm was observed because enough perfect crystals, not susceptible to recrystallization, were obtained. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1949–1959, 2004     

Ion‐Pair SN2 Reaction of OH− and CH3Cl: Activation Strain Analyses of Counterion and Solvent Effects

We have theoretically studied the non‐identity S_N2 reactions of M_nOH^(n?1)+CH₃Cl (M⁺=Li⁺, Na⁺, K⁺, and MgCl⁺; n=0, 1) in the gas phase and in THF solution at the OLYP/6‐31++G(d,p) level using polarizable continuum model (PCM) implicit solvation. We want to explore and understand the effect of the metal counterion M⁺ and solvation on the reaction profile and the stereoselectivity of these processes. To this end, we have explored the potential energy surfaces of the backside (S_N2‐b) and frontside (S_N2‐f) pathways. To explain the computed trends, we have carried out analyses with an extended activation strain model (ASM) of chemical reactivity that includes the treatment of solvation effects.     

Molecular Clefts Derived from 9,9′-spirobi[9H-fluorene] for enantioselective complexation of pyranosides and dicarboxylic acids

The molecular clefts (R)- and (S)- 3 , incorporating 9,9′-spirobi[9H-fluorene] as a spacer and two N-(5,7-dimethyl-1,8-naphthyridin-2-yl)carboxamide (CONH(naphthy)) units as H-bonding sites were prepared via the bis(succinimid-N-yl esters) of (R)-and (S)-9,9′-spirobi[9H-fluorene]-2,2′-dicarboxylic acid ( 5 ). Derivative 6 , with one CONH(naphthy) unit and one succinimid-N-yl ester residue allowed easy access to spirobifluorene clefts with two different H-bonding sites, as exemplified by the synthesis of 4 . Binding studies with (R)- and (S)- 3 and optically active dicarboxylic acids in CDCl₃ exhibited differences in free energy of the formed diastereoisomeric complexes (Δ(ΔGº)) between 0.5 and 1.6 kcal mol^?1 (T 300 K). Similar enantioselectivities were observed with the spirobifluorene clefts (R)- and (S)- 1 , bearing two N-(6-methylpyridin-2-yl)carboxamide (CONH(py)) H-bonding sites. The thermodynamic quantities ΔHº and ΔSº for the recognition processes with (R)- and (S)- 1 were determined by variable-temperature ¹H-NMR titrations and compared to those with (R)- and (S)- 2 , which have two CONH(py) moieties attached to the 6,6′-positions of a conformationally more flexible 1,1′-binaphthyl cleft. All association processes showed high enthalpic driving forces which are partially compensated by unfavorable changes in entropy. Pyranosides bind to the optically active clefts 1 and 3 in CDCl₃ with ?ΔGº = 3.0–4.3 kcal mol^?1. Diastereoisomeric selectivities up to 1.2 kcal mol^?1 and enantioselectivities up to 0.4 kcal mol^?1 were observed. Cleft 4 and N-(5,7-dimethyl-1,8-naphthyridin-2-yl)acetamide ( 25 ) complexed pyranosides 22–24 as effectively as 3 indicating that only one CONH(naphthy) site in 3 associates strongly with the sugar derivatives. Based on the X-ray crystal structure of 3 , a computer model for the complex between (S)- 3 and pyranoside 22 was constructed. Molecular-dynamics (MD) simulations showed that differential geometrical constraints are at the origin of the high enantioselectivity in the complexation of dicarboxylic acid (S)- 7 by (R)- and (S)- 1 and (R)- and (S)- 3 .     

Computational insight into the reaction intermediates in the glycosylation reaction assisted by donor heteroatoms

We studied the geometric and electronic structure of several cations (9 and 18-23) that are usually proposed as intermediates for glycosylation reactions using DFT methods. For ions 9 and 18-23 the geometries obtained corresponded to an open ion (6b type) irrespective of the exocyclic heteroatom (S, Se, I) and the size of the cycle (furanoses as well as pyranoses). We studied how substituents bonded to the exocyclic heteroatom (R in SR and SeR) affect the structure of ions and found that the geometry approached that of episulfonium and episelenonium ions (6a type) when the substituents were electron donors. The tert-butyl group and the 2,4,6-trimethyl- and 2,4,6-trimethoxyphenyl and trimethylsilyl groups produced the strongest of these effects. The presence of an electron-withdrawing group (CO-CF(3)) bonded to the hydroxymethyl group produced a similar but weaker effect. We analyzed this behavior in terms of molecular orbital interactions.     

Application of flow chemistry to the reduction of nitriles to aldehydes

Reduction of nitriles to aldehydes with diisobutylaluminium hydride (DIBAL-H) is an important transformation in organic chemistry. But the use of this reaction is limited for the lack of reproducibility due to the instability of the intermediates formed. In the current article we disclose the improvement of the reaction applying continuous flow technology.