Readout error is a final labeling step, so the lesson applies a calibrated assignment matrix after the state budget rather than mixing it into the quantum part. The fractions are exact for this pinned count model, while real readout rows come from calibration data whose thresholds, drift, and finite-shot noise limit the certainty.
Readout assignment is a separate classical matrix after the quantum state budget. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Readout error has its own calibration rows
The readout assignment rows are 9/10, 1/10 and 1/5, 4/5.
A=[1095110154]
Readout rows are applied after the state budget
The calibration rows stay separate from the true state probabilities until the prediction step.