Average and Scope

Honest SPT Scope

SPT is exact here because the scheduling model is deliberately small.

highlighted = computed this step

Exact improvement

The total-completion-time improvement is 3.

improvement=3\text{improvement}=3
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3

Simple scope

The model has one machine, all jobs ready, no setup, and no preemption.

single machine, all ready, no setup\text{single machine, all ready, no setup}
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3

Not modeled

It does not model due dates, release dates, setup times, parallel machines, priorities, or uncertainty.

outside this model: due dates and uncertainty\text{outside this model: due dates and uncertainty}
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3

Honesty note

SPT is exact for this all-ready single-machine total-completion-time objective. It does not model due dates, release dates, setup times, parallel machines, priorities, or uncertainty. Pixel positions are rounded for layout; every processing time, completion time, total, and average is exact.

exact arithmetic inside the all-ready SPT model\text{exact arithmetic inside the all-ready SPT model}
Average and scopeThe same totals also give exact average flow times.averages and scopeimprovement 3OriginalA p=3C=3B p=1C=4C p=2C=606SPTB p=1C=1C p=2C=3A p=3C=606completion tablejoboriginal CSPT CA36B41C63totals 13 -> 10averages 13/3 -> 10/3