Derivation and Formal Proof of Floyd-Warshall Algorithm

Author(s):  
Zhengkang Zuo ◽  
Xiaodan Liu ◽  
Qing Huang ◽  
Yunyan Liao ◽  
Yuan Wang ◽  
...  
Keyword(s):  
Author(s):  
Rob Nederpelt ◽  
Herman Geuvers
Keyword(s):  

Author(s):  
Dang Duy Bui ◽  
Kazuhiro Ogata

AbstractThe mutual exclusion protocol invented by Mellor-Crummey and Scott (called MCS protocol) is used to exemplify that state picture designs based on which the state machine graphical animation (SMGA) tool produces graphical animations should be better visualized. Variants of MCS protocol have been used in Java virtual machines and therefore the 2006 Edsger W. Dijkstra Prize in Distributed Computing went to their paper on MCS protocol. The new state picture design of a state machine formalizing MCS protocol is assessed based on Gestalt principles, more specifically proximity principle and similarity principle. We report on a core part of a formal verification case study in which the new state picture design and the SMGA tool largely contributed to the successful completion of the formal proof that MCS protocol enjoys the mutual exclusion property. The lessons learned acquired through our experiments are summarized as two groups of tips. The first group is some new tips on how to make state picture designs. The second one is some tips on how to conjecture state machine characteristics by using the SMGA tool. We also report on one more case study in which the state picture design has been made for the mutual exclusion protocol invented by Anderson (called Anderson protocol) and some characteristics of the protocol have been discovered based on the tips.


2007 ◽  
Vol 101 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Daniel Bodansky ◽  
Kevin Jon Heller

Prosecutor v. Karemera, Ngirumpatse, & Nzirorera. Case No. ICTR-98-44-AR73(C). Decision on Prosecutor's Interlocutory Appeal of Decision on Judicial Notice. At <http://www.ictr.org>.International Criminal Tribunal for Rwanda, Appeals Chamber, June 16, 2006.In an interlocutory appeal in Prosecutor v. Karemera, the appeals chamber of the International Criminal Tribunal for Rwanda (ICTR) held that the commission of genocide against the Tutsis in 1994 is a “fact of common knowledge” of which trial chambers must take judicial notice (Appeals Decision, paras. 35, 38). The decision represents a significant reversal in ICTR practice: although some trial chambers have been willing to take notice of “widespread and systematic attacks” against Tutsis in Rwanda, they have uniformly insisted that the question of whether the attacks amounted to genocide is so fundamental that formal proof is required.As noted in the indictment, Edouard Karemera and Jospeh Nzirorera were minister-level officials in the Rwanda’ interim government (Indictment, paras. 1, 3) and served, along with Mathieu Ngirumpatse, as the national executive leadership of the National Republican Movement for Democracy and Development (MRND) (id., para. 9). They are charged with, inter alia, conspiracy to commit genocide, direct and public incitement to commit genocide, genocide, and—alternatively—complicity in genocide (id.). The prosecution alleges that they created, recruited, and organized the Interahamwe, the vicious youth wing of the MRND; provided members of the Interahamwe with weapons and military training; and helped formulate and implement policies of the interim government of April 8, 1994, that were intended to incite, encourage, and abet killings of Tutsis (id., para. 14).


2016 ◽  
Vol 10 (3) ◽  
pp. 583-601 ◽  
Author(s):  
WILFRID HODGES

AbstractIbn Sīnā (11th century, greater Persia) proposed an analysis of arguments by reductio ad absurdum. His analysis contains, perhaps for the first time, a workable method for handling the making and discharging of assumptions in a formal proof. We translate the relevant text of Ibn Sīnā and put his analysis into the context of his general approach to logic.


1979 ◽  
Vol 16 (3) ◽  
pp. 646-650 ◽  
Author(s):  
Roy Saunders ◽  
Claude Lefèvre ◽  
Richard J. Kryscio

We provide a formal proof of a conclusion due to Abakuks (1974) which states that the expected number of survivors in Downton's carrier-borne epidemic model approaches the limit (ρ /π)δ as the initial number of susceptibles tends to infinity. Here ρ denotes the relative removal rate for carriers, π denotes the conditional probability that an infected susceptible will become a carrier, δ denotes the Kronecker delta function and denotes the initial number of carriers.


2007 ◽  
Vol 82 (5) ◽  
pp. 2056-2064 ◽  
Author(s):  
Luka Čičin-Šain ◽  
Zsolt Ruzsics ◽  
Juergen Podlech ◽  
Ivan Bubić ◽  
Carine Menard ◽  
...  

ABSTRACT Genes that inhibit apoptosis have been described for many DNA viruses. Herpesviruses often contain even more than one gene to control cell death. Apoptosis inhibition by viral genes is postulated to contribute to viral fitness, although a formal proof is pending. To address this question, we studied the mouse cytomegalovirus (MCMV) protein M36, which binds to caspase-8 and blocks death receptor-induced apoptosis. The growth of MCMV recombinants lacking M36 (ΔM36) was attenuated in vitro and in vivo. In vitro, caspase inhibition by zVAD-fmk blocked apoptosis in ΔM36-infected macrophages and rescued the growth of the mutant. In vivo, ΔM36 infection foci in liver tissue contained significantly more apoptotic hepatocytes and Kupffer cells than did revertant virus foci, and apoptosis occurred during the early phase of virus replication prior to virion assembly. To further delineate the mode of M36 function, we replaced the M36 gene with a dominant-negative FADD (FADDDN) in an MCMV recombinant. FADDDN was expressed in cells infected with the recombinant and blocked the death-receptor pathway, replacing the antiapoptotic function of M36. Most importantly, FADDDN rescued ΔM36 virus replication, both in vitro and in vivo. These findings have identified the biological role of M36 and define apoptosis inhibition as a key determinant of viral fitness.


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