Clearing a Night Picket Roster Against Standing Instructions
The duty clerk of a border company must detail six constables - A, B, C, D, E and F - to three night pickets, Picket 1, Picket 2 and Picket 3, for the hours 2200 to 0600. Each picket is to be manned by exactly two constables. The following standing instructions apply: (i) A and F must be on the same picket, since only they are trained on the new night-vision device; (ii) A and D must not be on the same picket because of a pending disciplinary enquiry; (iii) B must share a picket with C or with F; (iv) D must not be posted to Picket 3, which needs a steep climb to a height of 40 m; (v) if C is posted to Picket 2, then E must be posted to Picket 3. The clerk submits this draft: Picket 1 - A and D; Picket 2 - B and F; Picket 3 - C and E. The company havildar major must clear the roster by 1800, and at 2000 B reports sick.
1. Test the clerk's draft against the standing instructions and produce a correct roster, showing how you derived it rather than guessing.
Read the worked answer
Test the draft. Picket 1 holds A and D, which breaks instruction (ii) outright. It also means A is not with F anywhere, breaking instruction (i). Two violations, so the draft cannot be cleared.
Derive the roster. Instruction (i) fixes the block {A, F}. Only the remaining four can move.
Instruction (iv) keeps D out of Picket 3, and A's picket is already full, so D must go to Picket 2 with one of B, C or E.
- Try {D, B} at Picket 2. Then B is with neither C nor F, breaking (iii). Reject.
- Try {D, C} at Picket 2. Instruction (v) then forces E to Picket 3, leaving B with E there - again breaking (iii). Reject.
- Try {D, E} at Picket 2. The remainder {B, C} goes to Picket 3, satisfying (iii); C is not at Picket 2, so (v) is not triggered; D is out of Picket 3. Accept.
Valid pairing: {A, F}, {D, E}, {B, C}.
One refinement the draft never reaches: {B, C} must not be placed on Picket 2, because (v) would then demand E on Picket 3 while E is fixed with D. So {A, F} and {D, E} may swap between Pickets 1 and 2, but {B, C} belongs on Picket 1 or 3. Stating that shows the solution is complete and not merely one lucky arrangement.
2. At 1700 a fresh instruction arrives: E must share a picket with A. Show what happens and recommend how the difficulty should be resolved, with reasons.
Read the worked answer
Show the contradiction. Instruction (i) already puts A with F, and a picket holds exactly two men. Adding 'E with A' would require A, F and E on one picket - three men in a two-man slot. The constraint set is therefore inconsistent, and no roster exists. This is not a hard puzzle; it is an impossible one, and reporting it as impossible is the correct answer.
Options, with the cost of each:
- Relax (i) - the cleanest. Pair {A, E}, then {C, D} and {B, F}. Check: A and D apart (ii holds); B with F (iii holds); D not on Picket 3 (iv holds, put {C, D} on Picket 1); C not on Picket 2, so (v) is silent. Cost: the night-vision device sits with A, and F is without it - acceptable only if A can hand it over or a second device is issued.
- Relax the two-man rule for one picket - put A, F and E on Picket 3 and single-man another. Cost: a picket with one man is a real operational weakening at night, and it quietly trades a training convenience against a security duty.
- Add a seventh man - restore the two-man structure without dropping any instruction.
Recommend option 1 with a check on the night-vision device, and option 3 if a spare man is available, because it resolves the conflict without weakening any rule. Never resolve it by silently ignoring a standing instruction.
3. At 2000 B reports sick and no replacement is immediately available. What is the correct course of action?
Read the worked answer
State the arithmetic plainly. Three pickets at two men each require six. With B sick, five remain, so one picket will be short. The shortfall is a fact, not a matter of preference, and the decision is not the clerk's to make quietly.
Sequence of action:
- Inform the duty officer at once and record the sickness and the time in the General Diary, so that the decision is traceable.
- Ask for a relief from the nearest available pool - quartermaster's staff, MT drivers, the battalion reserve, or the neighbouring post. This is the correct first remedy and is usually available.
- If no relief comes before 2200, do not simply leave a picket unmanned and say nothing. Recommend to the officer which picket is thinned: the one covering the least likely approach, and never the picket whose loss leaves a dead ground unobserved, given Picket 3 requires the 40 m climb.
- Notify battalion of the reduced picket state, so that the gap is known to the net rather than discovered by an inspection.
- On B's recovery, restore the sanctioned roster rather than inventing a new pattern, and note the deviation in the log with the reason.
Reasoning to state in the answer: a roster is a written promise about who is watching which approach. Breaking that promise silently at 2000 is the real error; breaking it openly, with the officer's authority and a log entry, is a command decision made at the right level.