Build a lid fault decision table and test it against five described symptoms

applied · 70 min · Objective 1.1

Task

Turn the four lid systems into a decision table that maps a symptom to a component and a confirming test, then run the table against five symptom descriptions and record where it was ambiguous. A table that answers every case is usually a table that is not being honest about ambiguity.

Steps

  1. Write lab/lid/decision.csv with header symptom,component,confirming_test,cost and at least eight rows. cost is free, minutes or parts.
  2. Order the rows so that free tests come before tests requiring parts, and record in lab/lid/ordering.md why that ordering is not the same as ordering by likelihood.
  3. Write five symptom descriptions into lab/lid/cases.txt, one per line, each precise enough to be decidable -- for example 'image present, no touch response, buttons work'.
  4. For each case, record in lab/lid/answers.csv with header case,component,test,ambiguous_with the component your table names, the test, and any other component the symptom could equally indicate.
  5. At least one of your five cases must be genuinely ambiguous. Record in lab/lid/ambiguity.md what additional observation would resolve it.

Verify

awk -F, 'NR>1 && NF>=4 {n++} END {print n" decision row(s)"}' lab/lid/decision.csv
awk -F, 'NR>1 {print $4}' lab/lid/decision.csv | sort -u | wc -l
grep -c . lab/lid/cases.txt
awk -F, 'NR>1 && NF>=4 {n++} END {print n" case(s) answered"}' lab/lid/answers.csv
awk -F, 'NR>1 && $4!="" && $4!="none" {n++} END {print n+0" ambiguous case(s)"}' lab/lid/answers.csv
grep -c . lab/lid/ambiguity.md

Eight or more decision rows across at least two cost bands, five cases, five answers, and at least one ambiguous case with a resolving observation. A table with zero ambiguous cases has not been tested against a hard enough case.

Notes

Keep this table. Lesson 38 builds the display version of the same thing, and lesson 45 collects every table in the course into one symptom-to-tool map.

This is an independent study companion for CompTIA A+ Core 1 220-1201 and is not produced by or endorsed by CompTIA.