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Teoria di Putnam

Teoria di Putnam. Un tentativo di giustificare la valutazione di E, T e P con un modello matematico che fornisce una sorta di legge fondamentale ( Equazione del Software ) Una serie d’impatti interessanti (in particolare quello del tempo minimo di delivery ).

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Teoria di Putnam

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  1. Teoria di Putnam • Un tentativo di giustificare la valutazione di E, T e P con un modello matematico che fornisce una sorta di legge fondamentale (Equazione del Software) • Una serie d’impatti interessanti (in particolare quello del tempo minimo di delivery)

  2. Norden/Rayleigh distribution for H-resources usage a=2 Max number of h-resources in the project a=.5 a=.25 a=.125

  3. Full Effort K and Development Effort E E=K*0,4

  4. Difficulty Factor Difficulty

  5. Productivity Equation • Foundation of the Putnam’s theory (productivity equation): • Empirically justified! • Combined with L=S/E, productivity equation leads to thesoftware equation Cn is a technology constant

  6. The Software Equation C is a technology constant (type of project) K – effort in man years including maintenance T- development time in years S - size of software in LOC E=K*0,4 C - 1500 for real-time embedded, 4984 for batch, 10040 for well-supported, organized environment For a given project (because S is fixed) Pressman version of software equation:

  7. Minimal Time to Deliver For a given type of project (a constraint): same as If cost2 and C are known, than it is possible to estimate K and T given S (T is then called theminimal time to deliver, before this minimal T the project would probably fail) Pressman version for minimal time to deliver and related effort: Per I valori di PP e B vedere https://www.dacs.dtic.mil/techs/estimation/comparison.php

  8. Classical Putnam’s Theory E Impossibile t Tmin T

  9. Personale e Tempo in Putnam • Aumentando P è possibile diminuire T: • Ciò è vero solo se tutti i P contribuiscono effettivamente alla definizione delle LOC

  10. Impact I Estimate delivery of DLOC New effort to deliver on time T Estimated effort to deliver by T Tmin T1 T(DLOC)+T1 T(LOC)

  11. Impact II Maximal personal productivity (per type of software) Lp; each person contribute to deliver S lines of code, L<= Lp Estimate delivery of DLOC New efforts to deliver on time T Estimated effort to deliver by T Tmin T1 T(LOC) T(DLOC)+T1

  12. Impact III E t Tmax Tmin T(LOC)

  13. Impact on Planning • The minimal delivery time can be interpreted as the maximal parallel decomposition in tasks for a given project • Indeed, project management tends to parallelize tasks as much as possible Develop the module A (accessing the DB) Develop the DB structure Develop the module B(accessing the DB) Tmin T(LOC)

  14. Time to deliver and Tasks • Parallel tasks in a project plan can degenerate in a sequence if the number of h-resources are reduced Develop the DB structure Develop the module A (accessing the DB) If the programmer is the same person Develop the module B (accessing the DB) Develop the module A (accessing the DB) Develop the DB structure Develop the module B(accessing the DB) T(LOC) T’(LOC)

  15. Delivery time, Project Plan and Personnel • It is very difficult adding personnel and changing project plans trying to parallellise tasks Develop the module A (accessing the DB) Develop the DB structure Develop the module B(accessing the DB) Develop the DB structure Unplanned Communication Task Develop the module A (accessing the DB) Develop the module B (accessing the DB) T(LOC) T’(LOC)

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