General Report on Tunny

    Instead the operator uses C3, i.e. 4=5=/1=2. R 1259 is the number of places looked at, i.e. of places where 1=2. A, the expected random number of places where 4=5=/1=2 is a quarter of this, because two more conditions are imposed, and .

    ST as above.

    The best score is 4.15σ. It should be noticed that three scores above the set total have Χ₄ at 05; and that the Χ₄ settings are 22, 22+7, 22+14, suggesting a wheel-slide [23G] of 7 on Χ₄, but fortunately one too weak to make the setting really doubtful.

    The most likely letters to set Χ's are /, 5, U: to decide which the operator counts / & 9, 5 & 8, U & K; and because 5 & 8 are numerous (212) chooses 5

    A and σ are as before, but ST is now only A+σ, because this is a one-wheel run.

    The setting obtained is "certain".

K1 K2 K3 K4 K5 40 28  08  05 22

is printed by means of P.M.H. so that errors in Colossus

setting will be manifest.

    AG X2 XX means against Χ₂=x.

    The settings for Χ₁ Χ₂ Χ₃ Χ₄ X₅ were not very strong, so that although the final Χ₃ score makes them "certain", it is just as well to inspect the letter count.

    This resolves all doubts as to the correctness of the settings, e.g. Χ₅ is made very certain by the scores for U>Q, 5>J, F>X. The count is in fact much better than average; the worst contradictions with the pairs in 23 H(e) are CM, DB, ZE.

    The dossier is therefore marked all certain.

    The letters have been inserted in the letter count for the purpose of this report: Colossus operators knew them too well to need this.

    The pen entries at the right of the letter count are the DO's order for a motor run [which appears on the next page but one.]

    The part 4500 - end is not yet set: it is believed that there is a message slide so that the settings for all chi's in the part of the message will be increased, or decreased, equally.