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INGINERIE SOFTWARE. Ştefan Stăncescu. CURSUL 2.2 Legile lui Lehman. CURSUL 2.2- LEGILE LUI LEHMAN. I - Continuing Change II - Increasing Complexity III - Self Regulation IV - Conservation of Organisational Stability V - Conservation of Familiarity VI - Continuing Growth
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INGINERIE SOFTWARE Ştefan Stăncescu
CURSUL 2.2 Legile lui Lehman. INGINERIA SOFTWARE StSt
CURSUL 2.2- LEGILE LUI LEHMAN I - Continuing Change II - Increasing Complexity III - Self Regulation IV - Conservation of Organisational Stability V - Conservation of Familiarity VI - Continuing Growth VII - Declining Quality VIII - Feedback System INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN I - Continuing Change A program that is used must be continually adapted else it becomes progressively less satisfactory Un produs program software PPSW operational trebuiecontinuuadaptat altfeldevine din ce in cemaiputineficient (realitateainitiala la t=0 se modifica in t) INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN II - Increasing Complexity As a program is evolved its complexity increases unless work is done to maintain or reduce it. Daca un PPSWevolueaza complexitatea sa creste deci trebuiesc activitati de a mentine sau reduce complexitatea (termodinamica modificarilor – entropia creste, modificarile se suprapun – reproiectare tot) INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN III - Self Regulation The program evolution process is self regulating with close to normal distribution of measures of product and process attributes Procesul de evolutie al unui PPSW esteautoreglabil, legat de distributiauniforma a facilitatilormodificate ale PPSW parametrilorfacilitatilor PPSW (Cantitatea de facilitati se ofera constant in timp) INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN IV - Conservation of Organisational Stability The average effective global activity rate on an evolving system is invariant over the product life time. Activitatea de modificare a evolutieiunui PPSW esteconstanta in medie pe tot ciclul de viata al PPSW (cantitatea de efort organizational se pastreaza) INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN V - Conservation of Familiarity During the active life of an evolving program, the content of successive releases is statistically invariant In ciclul de viataoperationala a unui PPSW continutulnou al versiunilorsuccesive este invariant statistic (cantitatea de nou e constanta) INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN VI - Continuing Growth Functional content of a program must be continually increased to maintain user stisfaction over its lifetime Facilitatileunui PPSW trebuiescmereu mărite pentru a mentinesatisfactiautilizatorului cat maimulttimp (mereutrebuiesa se oferefacilitati in plus sauimbunatatite) INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN VII - Declining Quality Programs will be perceived as of declining quality unless rigorously maintained and adapted to a changing operational environment Se va sesiza descresterea calitatii PPSW daca nu este bine mentinut si adaptat dupa schimbarea environmentului INGINERIA SOFTWARE StSt
CURSUL 2- LEGILE LUI LEHMAN VIII - Feedback System Programming Processes constitute Multi-loop, Multi-level Feedback systems and mustbe treated as such to be successfully modified or improved Procesul de creare/instalare/operare/mentenanta e sistem cu multe bucle de reactie si este el insusi modificabil pentru a mentine adaptarea INGINERIA SOFTWARE StSt