[Solved] Combinatorial Design; Block Design

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RoryOF
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Re: [Solved] Maths question - Is it possible ?

Post by RoryOF »

If your computer continues to refuse to load OpenOffice, start TaskManager (Ctrl Shift Esc) and kill any soffice processes shown on TaskManager's tabs.
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Lupp
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Re: [Solved] Maths question - Is it possible ?

Post by Lupp »

Silvabod wrote:... I just followed it through. Just replacing the U and V with reserve letters doesn't guarantee uniqueness, I found one duplicate already ... Perhaps you would run it again, please, with just 20 and 21 characters ?
I didn't "run it", but tinkered the published solution for "20+2" based on a roughly plausible stragety which aimed at a "20+0" solution, but failed to get one. With different words: To have the 2 spare players at disposition to avoid final conflicts was essential to get a solution at all. In fact I doubt if there are any "20+0" and "20+1" solutions, but I cannot offer a proof for the contrary.
Doubting the existence of solutions was the reason to inist in getting shown what you thought was a solution.
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Re: [Solved] Maths question - Is it possible ?

Post by Silvabod »

I'm now 79 as of a few days ago. My maths education was basic "O" level (to 1958, when I left school) Needed formal spreadsheet training for business - was literally just half-a-day on 1 2 3 (IBM?) in about 1980. Changed to Excel a few years later, since used them sparingly on various business and personal projects. Early retired/redundant in 1999, now occasionally use OpenOffice Calc on private leisure projects such as this which tweak my interest, asking for help as needed Have had NO training whatsoever in LOGIC. All this explains that I am unable to converse technically/sensibly on spreadsheet coding.

LOGIC - you have proved the solution to 20 + 2 in 5 groups of 4 with 2 over, no pairs duplicated and no substitute more than once. You have also stated that 22 is the outside edge/limit, so for 23 or greater it won't work. You're now saying you've not found solutions for lesser numbers either, and doubt there is one. I can't doubt you (no basis to), but it does seem to defy logic ! However, I do appreciate the substantial work you have put in, and thank you for it. The original question is fully answered - matter closed?
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Silvabod
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Re: [Solved] Maths question - Is it possible ?

Post by Silvabod »

Silvabod wrote:If your computer continues to refuse to load OpenOffice, start TaskManager (Ctrl Shift Esc) and kill any soffice processes shown on TaskManager's tabs.
Thanks for the OO load failure advice, useful to know !
OpenOffice 4.1.5 on Windows 10
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