Gettier Problems and Logical Properties of Justification

In the classical account of knowledge, S knows that P if and only if S believes that P, S is justified in believing that P, and P is true (JTB).. In 1963, Gettier presented two problems that casted doubt on this account. Since then, numerous authors proposed modifications or clarifications of JTB, however, these efforts have not produced a satis-factory solution. In this paper, the focus is on logical properties of justification. The Get-tier problem Case II is expressed in sentential logic and Gettier Minimal Assumption (GMA) is introduced. It is shown that Gettier must have used GMA or some other as-sumption that entails GMA in his construction of Case II. Rejection of GMA solves Get-tier problem Case II and it is a step towards a better understanding of the logical proper-ties of justification and knowledge

Bohemian circular structure, Czechoslovakia: Search for the impact evidence

Test of the impact hypothesis for the origin of the circular, 260-km-diameter structure of the Bohemian Massif led to the discovery of glasses and breccias in the Upper Proterozoic sequence that can be compared to autogeneous breccias of larger craters. The black recrystallized glass contains small exsolution crystals of albite-oligoclase and biotite, regularly dispersed in the matrix recrystallized to quartz. The occurrence of these rocks is limited to a 1-sq-km area. It is directly underlain by the breccia of the pelitic and silty rocks cemented by the melted matrix, found on several tens of square kilometers. The melt has the same chemistry as rock fragments in major and in trace elements. It is slightly impoverished in water. The proportion of melted rocks to fragments varies from 1:5 to 10:1. The mineralogy of melt viens is the function of later, mostly contact metamorphism. On the contact of granitic plutons it abounds on sillimanite, cordierite, and small bullets of ilmenite. Immediately on the contact with syenodiorites it contains garnets. The metamorphism of the impact rock melt seems the most probable explanation of the mineralogy and the dry total fusion of rocks accompanied by the strong fragmentation. Other aspects of this investigation are discussed

Members of the Austro-Hungarian Air Force from the Czech Lands

Toto pojednání si klade za cíl nastínit podíl letců z českých zemí na formování, organizační a personální výstavbě, technickém rozvoji a na operačním nasazení rakousko- uherského letectva v období předcházejícímu vzniku 1. světové války a zejména v jejím průběhu. Zároveň se pokusí o stanovení jejich percentuálního podílu v celém rakousko- uherském armádním i námořním letectvu. Národnostní (či zemská) problematika u rakousko-uherského letectva nebyla dosud předmětem historického výzkumu v žádném z nástupnických států. Důvodem byl fakt, že u této mladé zbraně nebyla - na rozdíl od jiných zbraní - statisticky sledována. Pro rakouskou historiografii nepředstavovalo národnostní složení c. a k. letectva téma hodné přiměřené pozornosti. V české, respektive československé se na dlouhou dobu prosadila dobově podmíněná teze o tom, že čeští letci byli v rakousko-uherských leteckých silách zastoupeni "v nepatrném počtu". Tato letitá teze, která ovšem nikdy nebyla věrohodně doložena, je v této práci podrobena kritice, vedoucí k jejímu přehodnocení. Především rekonstrukcí a analýzou statisticky relevantních vzorků osob došlo ke zjištění, že ve skutečnosti zastoupení letců z českých zemí bylo nadprůměrné a Češi v něm měli solidní zastoupení. Přesto však nikoli takové, jaké by odpovídalo jejich národnostnímu...The aim of this paper is to outline the share of airmen from the Czech lands in the formation, organizational and personnel construction, technical development and operational deployment of the Austro-Hungarian Air Force in the pre-war period and especially during World War 1. Simultaneously, this work will also try to determine their percentage share in the entire Austro-Hungarian Army and Naval Air Forces. The national (or provincial) origin of the personel of the Austro-Hungarian Air Force has not yet been the subject of historical research in any of the successor states. The reason was the fact that this young weapon was not statistically monitored - unlike other weapons. For Austrian historiography, the ethnic composition of the Austro-Hungarian aviation was not a subject of adequate attention. In Czech and Czechoslovakian historiography, for a long time, it was stated that number of the Czech airmen in the Austro-Hungarian Air Force was "insignificant". However, this age-old thesis, which has never been credibly proven, is subject to criticism in this work, leading to its re-evaluation. In particular, the reconstruction and analysis of statistically relevant samples of people revealed that in fact the representation of airmen from the Czech lands was above average and the Czechs had a solid...Institute of General HistoryÚstav světových dějinFilozofická fakultaFaculty of Art

Stepwise refinement revisited

In this paper, rigorous application of stepwise refinement is explored. The steps of definition, decomposition, and completion are described, where completion is a newly introduced step. This combination of steps extends the use of stepwise refinement to larger systems. The notions of range, active objects, and backlog interface are introduced. Verification of incomplete programs via interactive testing is described. The paradigm is demonstrated in an example. The relationship between the paradigm and the current programming languages is considered. It is argued that the WHILE-DO loop is a harmful construct from this point of view.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25759/1/0000320.pd

Agent-based simulation of open source evolution

We present an agent-based simulation model developed to study how size, complexity and effort relate to each other in the development of open source software (OSS). In the model, many developer agents generate, extend, and re-factor code modules independently and in parallel. This accords with empirical observations of OSS development. To our knowledge, this is the first model of OSS evolution that includes the complexity of software modules as a limiting factor in productivity, the fitness of the software to its requirements, and the motivation of developers. Validation of the model was done by comparing the simulated results against four measures of software evolution (system size, proportion of highly complex modules, level of complexity control work, and distribution of changes) for four large OSS systems. The simulated results resembled the observed data, except for system size: three of the OSS systems showed alternating patterns of super-linear and sub-linear growth, while the simulations produced only super-linear growth. However, the fidelity of the model for the other measures suggests that developer motivation and the limiting effect of complexity on productivity have a significant effect on the development of OSS systems and should be considered in any model of OSS development