i'm glad to see that there is still some interest in the muffin/common
refinement of partitions problem.
some time ago, veit elser gave the upper bound T(m, n) <= 1/(3m)
for m < n < 3m/2 , and noted that some of the values he found
achieved this bound. i looked at this range more closely and found
that i could improve the upper bound as follows.
here t denotes a positive integer.
if ((3t+1)/(3t))m < n <= ((3t)/(3t-1))m , then T(m, n) <= 1/(3n) .
if ((3t+2)/(3t+1))m < n <= ((3t+1)/(3t))m , then
T(m, n) <= (t+1)/(2n) - t/(2m) .
if ((3t+3)/(3t+2))m < n < ((3t+2)/(3t+1))m , then
T(m, n) <= (t+1)/(4m) - t/(4n) .
if ((3t+3)/(3t+2))m = n , then T(m, n) <= 1/(3m) .
(here, as in previous messages, i am using T(m, n) = maximum c
such that there is a common refinement of 1/m + 1/m + ... + 1/m = 1
and of 1/n + 1/n + ... + 1/n = 1 , with all parts >= c .)
the first three cases are all improvements over veit's bound.
in the fourth case, where there is no improvement, equality is always
attained by veit's construction for T(3t+2, 3t+3) , and by obvious
extension to T((3t+2)k, (3t+3)k) . however, the above shows that
this is the exception, rather than the rule.
i find the first case interesting, because i have not seen any cases
(with m <= n ) where T(m, n) is strictly less than 1/(3n) .
if we allow parts of size 1/(3n) , we may split some of the 1/n 's
into 3 parts, and that seems to allow a lot of flexibility.
in fact, the only occurrences of T(m, n) = 1/(3n) i've seen are
those from the first case above. so i conjecture that equality always
holds in the first case.
on the other hand, the bounds in the other cases cannot always be
attained. they can be attained if n = m+1 , by veit's and moulton's
constructions. they can also be attained if n = m+2 by similar
constructions. however, if n >= m + 3 , there are cases that require
more careful analysis and for which the upper bound can be lowered;
the first such case is (13, 16) . when n = m + 3 , it seems that
the upper bound can be attained in all cases except when m = 4 mod 9 ;
in that case the exact value is T(9k+4, 9k+7) = (9k+5)/(3(9k+4)(9k+7))
for k >= 1 .
below are some data i calculated, all by pencil and paper, so subject
to a small possibility of error. obviously this amount of data starts
to become unwieldy; corrections and/or confirmations are welcome!
i believe i have a proof for each of these values, but may have given
short shrift to some subcases i thought couldn't give optimal partitions.
mike
T(2, 3) = 1/6
T(2, 4) = 1/4
T(3, 4) = 1/12
T(2, 5) = 1/10
T(3, 5) = 1/12
T(4, 5) = 3/40
T(2, 6) = 1/6
T(3, 6) = 1/6
T(4, 6) = 1/12
T(5, 6) = 1/15
T(2, 7) = 1/14
T(3, 7) = 5/84
T(4, 7) = 5/84
T(5, 7) = 1/21
T(6, 7) = 1/21
T(2, 8) = 1/8
T(3, 8) = 1/18
T(4, 8) = 1/8
T(5, 8) = 1/20
T(6, 8) = 1/24
T(7, 8) = 5/112
T(2, 9) = 1/18
T(3, 9) = 1/9
T(4, 9) = 7/144
T(5, 9) = 2/45
T(6, 9) = 1/18
T(7, 9) = 5/126
T(8, 9) = 1/24
T(2, 10) = 1/10
T(3, 10) = 2/45
T(4, 10) = 1/20
T(5, 10) = 1/10
T(6, 10) = 1/24
T(7, 10) = 1/30
T(8, 10) = 3/80
T(9, 10) = 1/30
T(2, 11) = 1/22
T(3, 11) = 1/24
T(4, 11) = 9/220
T(5, 11) = 13/330
T(6, 11) = 7/198
T(7, 11) = 1/28
T(8, 11) = 1/33
T(9, 11) = 13/396
T(10, 11) = 7/220
T(2, 12) = 1/12
T(3, 12) = 1/12
T(4, 12) = 1/12
T(5, 12) = 1/30
T(6, 12) = 1/12
T(7, 12) = 1/28
T(8, 12) = 1/24
T(9, 12) = 1/36
T(10, 12) = 1/30
T(11, 12) = 1/33
T(2, 13) = 1/26
T(3, 13) = 11/312
T(4, 13) = 11/312
T(5, 13) = 1/30
T(6, 13) = 1/30
T(7, 13) = 8/273
T(8, 13) = 1/32
T(9, 13) = 1/39
T(10, 13) = 7/260
T(11, 13) = 1/39
T(12, 13) = 1/39
T(2, 14) = 1/14
T(3, 14) = 1/30
T(4, 14) = 1/28
T(5, 14) = 11/350
T(6, 14) = 5/168
T(7, 14) = 1/14
T(8, 14) = 5/168
T(9, 14) = 1/36
T(10, 14) = 1/42
T(11, 14) = 2/77
T(12, 14) = 1/42
T(13, 14) = 9/364
T(2, 15) = 1/30
T(3, 15) = 1/15
T(4, 15) = 13/420
T(5, 15) = 1/15
T(6, 15) = 1/30
T(7, 15) = 1/35
T(8, 15) = 1/40
T(9, 15) = 1/36
T(10, 15) = 1/30
T(11, 15) = 1/45
T(12, 15) = 1/40
T(13, 15) = 3/130
T(14, 15) = 1/42
T(2, 16) = 1/16
T(3, 16) = 7/240
T(4, 16) = 1/16
T(5, 16) = 1/35
T(6, 16) = 1/36
T(7, 16) = 3/112
T(8, 16) = 1/16
T(9, 16) = 11/432
T(10, 16) = 1/40
T(11, 16) = 1/48
T(12, 16) = 1/48
T(13, 16) = 7/312
T(14, 16) = 5/224
T(15, 16) = 1/48
T(2, 17) = 1/34
T(3, 17) = 1/36
T(4, 17) = 15/544
T(5, 17) = 13/510
T(6, 17) = 13/510
T(7, 17) = 11/476
T(8, 17) = 1/40
T(9, 17) = 10/459
T(10, 17) = 2/85
T(11, 17) = 1/44
T(12, 17) = 1/51
T(13, 17) = 9/442
T(14, 17) = 5/238
T(15, 17) = 7/340
T(16, 17) = 11/544
T(2, 18) = 1/18
T(3, 18) = 1/18
T(4, 18) = 1/36
T(5, 18) = 1/40
T(6, 18) = 1/18
T(7, 18) = 1/42
T(8, 18) = 7/288
T(9, 18) = 1/18
T(10, 18) = 1/45
T(11, 18) = 1/44
T(12, 18) = 1/36
T(13, 18) = 1/54
T(14, 18) = 5/252
T(15, 18) = 1/45
T(16, 18) = 1/48
T(17, 18) = 1/51
T(2, 19) = 1/38
T(3, 19) = 17/684
T(4, 19) = 17/684
T(5, 19) = 16/665
T(6, 19) = 1/42
T(7, 19) = 25/1064
T(8, 19) = 13/608
T(9, 19) = 1/45
T(10, 19) = 11/570
T(11, 19) = 9/418
T(12, 19) = 1/48
T(13, 19) = 1/57
T(14, 19) = 1/57
T(15, 19) = 7/380
T(16, 19) = 1/57
T(17, 19) = 1/57
T(18, 19) = 1/57
T(2, 20) = 1/20
T(3, 20) = 1/42
T(4, 20) = 1/20
T(5, 20) = 1/20
T(6, 20) = 1/45
T(7, 20) = 3/140
T(8, 20) = 1/40
T(9, 20) = 1/45
T(10, 20) = 1/20
T(11, 20) = 13/660
T(12, 20) = 1/48
T(13, 20) = 1/52
T(14, 20) = 1/60
T(15, 20) = 1/60
T(16, 20) = 3/160
T(17, 20) = 1/60
T(18, 20) = 1/60
T(19, 20) = 13/760
T(2, 21) = 1/42
T(3, 21) = 1/21
T(4, 21) = 19/840
T(5, 21) = 1/45
T(6, 21) = 1/42
T(7, 21) = 1/21
T(8, 21) = 1/48
T(9, 21) = 5/252
T(10, 21) = 1/50
T(11, 21) = 4/231
T(12, 21) = 5/252
T(13, 21) = 1/52
T(14, 21) = 1/42
T(15, 21) = 1/63
T(16, 21) = 11/672
T(17, 21) = 2/119
T(18, 21) = 1/63
T(19, 21) = 13/798
T(20, 21) = 1/60
T(2, 22) = 1/22
T(3, 22) = 5/231
T(4, 22) = 1/44
T(5, 22) = 9/440
T(6, 22) = 1/48
T(7, 22) = 1/49
T(8, 22) = 9/440
T(9, 22) = 7/396
T(10, 22) = 13/660
T(11, 22) = 1/22
T(12, 22) = 7/396
T(13, 22) = 21/1144
T(14, 22) = 1/56
T(15, 22) = 1/66
T(16, 22) = 1/66
T(17, 22) = 3/187
T(18, 22) = 13/792
T(19, 22) = 13/836
T(20, 22) = 7/440
T(21, 22) = 1/66
T(2, 23) = 1/46
T(3, 23) = 1/48
T(4, 23) = 21/1012
T(5, 23) = 1/50
T(6, 23) = 19/966
T(7, 23) = 19/966
T(8, 23) = 17/920
T(9, 23) = 1/54
T(10, 23) = 17/920
T(11, 23) = 1/55
T(12, 23) = 13/828
T(13, 23) = 53/2990
T(14, 23) = 17/966
T(15, 23) = 1/60
T(16, 23) = 1/69
T(17, 23) = 1/69
T(18, 23) = 19/1242
T(19, 23) = 27/1748
T(20, 23) = 7/460
T(21, 23) = 29/1932
T(22, 23) = 15/1012
T(2, 24) = 1/24
T(3, 24) = 1/24
T(4, 24) = 1/24
T(5, 24) = 7/360
T(6, 24) = 1/24
T(7, 24) = 1/56
T(8, 24) = 1/24
T(9, 24) = 1/54
T(10, 24) = 1/60
T(11, 24) = 19/1056
T(12, 24) = 1/24
T(13, 24) = 5/312
T(14, 24) = 1/56
T(15, 24) = 1/60
T(16, 24) = 1/48
T(17, 24) = 1/72
T(18, 24) = 1/72
T(19, 24) = 9/608
T(20, 24) = 1/60
T(21, 24) = 5/336
T(22, 24) = 1/66
T(23, 24) = 1/69
T(2, 25) = 1/50
T(3, 25) = 23/1200
T(4, 25) = 23/1200
T(5, 25) = 1/25
T(6, 25) = 1/54
T(7, 25) = 1/56
T(8, 25) = 1/56
T(9, 25) = 4/225
T(10, 25) = 1/50
T(11, 25) = 19/1100
T(12, 25) = 1/60
T(13, 25) = 14/975
T(14, 25) = 17/1050
T(15, 25) = 1/60
T(16, 25) = 1/64
T(17, 25) = 1/75
T(18, 25) = 1/75
T(19, 25) = 13/950
T(20, 25) = 3/200
T(21, 25) = 1/75
T(22, 25) = 23/1650
T(23, 25) = 1/75
T(24, 25) = 1/75
T(2, 26) = 1/26
T(3, 26) = 1/54
T(4, 26) = 1/52
T(5, 26) = 1/55
T(6, 26) = 11/624
T(7, 26) = 1/56
T(8, 26) = 11/624
T(9, 26) = 19/1170
T(10, 26) = 1/60
T(11, 26) = 9/572
T(12, 26) = 1/60
T(13, 26) = 1/26
T(14, 26) = 4/273
T(15, 26) = 37/2340
T(16, 26) = 1/64
T(17, 26) = 1/68
T(18, 26) = 1/78
T(19, 26) = 1/78
T(20, 26) = 7/520
T(21, 26) = 11/819
T(22, 26) = 1/78
T(23, 26) = 4/299
T(24, 26) = 1/78
T(25, 26) = 17/1300
T(2, 27) = 1/54
T(3, 27) = 1/27
T(4, 27) = 25/1404
T(5, 27) = 23/1350
T(6, 27) = 1/54
T(7, 27) = 22/1323
T(8, 27) = 7/432
T(9, 27) = 1/27
T(10, 27) = 1/60
T(11, 27) = 17/1188
T(12, 27) = 7/432
T(13, 27) = 1/65
T(14, 27) = 5/378
T(15, 27) = 2/135
T(16, 27) = 13/864
T(17, 27) = 1/68
T(18, 27) = 1/54
T(19, 27) = 1/81
T(20, 27) = 1/81
T(21, 27) = 5/378
T(22, 27) = 4/297
T(23, 27) = 1/81
T(24, 27) = 1/72
T(25, 27) = 17/1350
T(26, 27) = 1/78
T(2, 28) = 1/28
T(3, 28) = 13/756
T(4, 28) = 1/28
T(5, 28) = 1/60
T(6, 28) = 1/60
T(7, 28) = 1/28
T(8, 28) = 1/56
T(9, 28) = 1/63
T(10, 28) = 11/700
T(11, 28) = 1/66
T(12, 28) = 5/336
T(13, 28) = 1/65
T(14, 28) = 1/28
T(15, 28) = 17/1260
T(16, 28) = 5/336
T(17, 28) = 1/68
T(18, 28) = 1/72
T(19, 28) = 1/84
T(20, 28) = 1/84
T(21, 28) = 1/84
T(22, 28) = 1/77
T(23, 28) = 33/2576
T(24, 28) = 1/84
T(25, 28) = 1/84
T(26, 28) = 9/728
T(27, 28) = 1/84
T(2, 29) = 1/58
T(3, 29) = 1/60
T(4, 29) = 27/1624
T(5, 29) = 26/1595
T(6, 29) = 25/1566
T(7, 29) = 1/63
T(8, 29) = 1/64
T(9, 29) = 41/2610
T(10, 29) = 21/1450
T(11, 29) = 1/66
T(12, 29) = 19/1392
T(13, 29) = 45/3016
T(14, 29) = 1/70
T(15, 29) = 16/1305
T(16, 29) = 19/1392
T(17, 29) = 27/1972
T(18, 29) = 1/72
T(19, 29) = 1/76
T(20, 29) = 1/87
T(21, 29) = 1/87
T(22, 29) = 15/1276
T(23, 29) = 49/4002
T(24, 29) = 17/1392
T(25, 29) = 17/1450
T(26, 29) = 1/87
T(27, 29) = 37/3132
T(28, 29) = 19/1624
T(2, 30) = 1/30
T(3, 30) = 1/30
T(4, 30) = 1/60
T(5, 30) = 1/30
T(6, 30) = 1/30
T(7, 30) = 13/840
T(8, 30) = 13/840
T(9, 30) = 2/135
T(10, 30) = 1/30
T(11, 30) = 1/66
T(12, 30) = 1/60
T(13, 30) = 11/780
T(14, 30) = 1/70
T(15, 30) = 1/30
T(16, 30) = 1/80
T(17, 30) = 7/510
T(18, 30) = 1/72
T(19, 30) = 1/76
T(20, 30) = 1/60
T(21, 30) = 1/90
T(22, 30) = 1/90
T(23, 30) = 4/345
T(24, 30) = 1/80
T(25, 30) = 1/75
T(26, 30) = 3/260
T(27, 30) = 1/90
T(28, 30) = 1/84
T(29, 30) = 1/87
T(2, 31) = 1/62
T(3, 31) = 29/1860
T(4, 31) = 29/1860
T(5, 31) = 1/65
T(6, 31) = 1/66
T(7, 31) = 25/1736
T(8, 31) = 25/1736
T(9, 31) = 23/1674
T(10, 31) = 1/70
T(11, 31) = 24/1705
T(12, 31) = 1/72
T(13, 31) = 21/1612
T(14, 31) = 3/217
T(15, 31) = 1/75
T(16, 31) = 17/1488
T(17, 31) = 20/1581
T(18, 31) = 11/837
T(19, 31) = 54/4123
T(20, 31) = 1/80
T(21, 31) = 1/93
T(22, 31) = 1/93
T(23, 31) = 1/93
T(24, 31) = 25/2232
T(25, 31) = 26/2325
T(26, 31) = 1/93
T(27, 31) = 37/3348
T(28, 31) = 19/1736
T(29, 31) = 1/93
T(30, 31) = 1/93
T(2, 32) = 1/32
T(3, 32) = 1/66
T(4, 32) = 1/32
T(5, 32) = 7/480
T(6, 32) = 7/480
T(7, 32) = 1/70
T(8, 32) = 1/32
T(9, 32) = 1/72
T(10, 32) = 1/70
T(11, 32) = 23/1760
T(12, 32) = 1/72
T(13, 32) = 5/416
T(14, 32) = 3/224
T(15, 32) = 1/75
T(16, 32) = 1/32
T(17, 32) = 19/1632
T(18, 32) = 11/864
T(19, 32) = 31/2432
T(20, 32) = 1/80
T(21, 32) = 1/84
T(22, 32) = 1/96
T(23, 32) = 1/96
T(24, 32) = 1/96
T(25, 32) = 11/1000
T(26, 32) = 7/624
T(27, 32) = 1/96
T(28, 32) = 5/448
T(29, 32) = 5/464
T(30, 32) = 1/96
T(31, 32) = 21/1984
T(2, 33) = 1/66
T(3, 33) = 1/33
T(4, 33) = 31/2112
T(5, 33) = 1/70
T(6, 33) = 1/66
T(7, 33) = 1/70
T(8, 33) = 1/72
T(9, 33) = 1/72
T(10, 33) = 3/220
T(11, 33) = 1/33
T(12, 33) = 3/220
T(13, 33) = 1/78
T(14, 33) = 23/1848
T(15, 33) = 13/990
T(16, 33) = 1/80
T(17, 33) = 2/187
T(18, 33) = 7/594
T(19, 33) = 47/3762
T(20, 33) = 49/3960
T(21, 33) = 1/84
T(22, 33) = 1/66
T(23, 33) = 1/99
T(24, 33) = 1/99
T(25, 33) = 17/1650
T(26, 33) = 3/286
T(27, 33) = 13/1188
T(28, 33) = 1/99
T(29, 33) = 10/957
T(30, 33) = 7/660
T(31, 33) = 7/682
T(32, 33) = 1/96
T(2, 34) = 1/34
T(3, 34) = 8/561
T(4, 34) = 1/68
T(5, 34) = 31/2210
T(6, 34) = 1/72
T(7, 34) = 29/2142
T(8, 34) = 15/1088
T(9, 34) = 29/2142
T(10, 34) = 13/1020
T(11, 34) = 1/77
T(12, 34) = 13/1020
T(13, 34) = 1/78
T(14, 34) = 11/952
T(15, 34) = 13/1020
T(16, 34) = 1/80
T(17, 34) = 1/34
T(18, 34) = 5/459
T(19, 34) = 23/1938
T(20, 34) = 1/85
T(21, 34) = 1/84
T(22, 34) = 1/88
T(23, 34) = 1/102
T(24, 34) = 1/102
T(25, 34) = 1/102
T(26, 34) = 9/884
T(27, 34) = 8/765
T(28, 34) = 5/476
T(29, 34) = 1/102
T(30, 34) = 7/680
T(31, 34) = 16/1581
T(32, 34) = 11/1088
T(33, 34) = 1/102
T(2, 35) = 1/70
T(3, 35) = 1/72
T(4, 35) = 33/2380
T(5, 35) = 1/35
T(6, 35) = 31/2310
T(7, 35) = 1/35
T(8, 35) = 29/2240
T(9, 35) = 4/315
T(10, 35) = 1/70
T(11, 35) = 1/77
T(12, 35) = 1/84
T(13, 35) = 64/5005
T(14, 35) = 1/70
T(15, 35) = 1/84
T(16, 35) = 1/80
T(17, 35) = 1/85
T(18, 35) = 19/1890
T(19, 35) = 22/1995
T(20, 35) = 1/84
T(21, 35) = 1/84
T(22, 35) = 1/88
T(23, 35) = 1/92
T(24, 35) = 1/105
T(25, 35) = 1/105
T(26, 35) = 1/105
T(27, 35) = 5/504
T(28, 35) = 3/280
T(29, 35) = 41/4060
T(30, 35) = 1/105
T(31, 35) = 43/4340
T(32, 35) = 11/1120
T(33, 35) = 3/308
T(34, 35) = 23/2380
T(2, 36) = 1/36
T(3, 36) = 1/36
T(4, 36) = 1/36
T(5, 36) = 1/75
T(6, 36) = 1/36
T(7, 36) = 1/77
T(8, 36) = 1/72
T(9, 36) = 1/36
T(10, 36) = 1/80
T(11, 36) = 5/396
T(12, 36) = 1/36
T(13, 36) = 29/2340
T(14, 36) = 1/84
T(15, 36) = 1/90
T(16, 36) = 7/576
T(17, 36) = 1/85
T(18, 36) = 1/36
T(19, 36) = 7/684
T(20, 36) = 1/90
T(21, 36) = 1/84
T(22, 36) = 1/88
T(23, 36) = 1/92
T(24, 36) = 1/72
T(25, 36) = 1/108
T(26, 36) = 1/108
T(27, 36) = 1/108
T(28, 36) = 5/504
T(29, 36) = 5/522
T(30, 36) = 1/90
T(31, 36) = 7/744
T(32, 36) = 1/96
T(33, 36) = 1/99
T(34, 36) = 1/102
T(35, 36) = 1/105
T(2, 37) = 1/74
T(3, 37) = 35/2664
T(4, 37) = 35/2664
T(5, 37) = 33/2590
T(6, 37) = 1/78
T(7, 37) = 33/2590
T(8, 37) = 1/80
T(9, 37) = 1/81
T(10, 37) = 1/80
T(11, 37) = 29/2442
T(12, 37) = 1/84
T(13, 37) = 28/2405
T(14, 37) = 1/84
T(15, 37) = 23/2220
T(16, 37) = 27/2368
T(17, 37) = 59/5032
T(18, 37) = 1/90
T(19, 37) = 20/2109
T(20, 37) = 23/2220
T(21, 37) = 103/9324
T(22, 37) = 9/814
T(23, 37) = 1/92
T(24, 37) = 1/96
T(25, 37) = 1/111
T(26, 37) = 1/111
T(27, 37) = 1/111
T(28, 37) = 19/2072
T(29, 37) = 61/6438
T(30, 37) = 16/1665
T(31, 37) = 1/111
T(32, 37) = 11/1184
T(33, 37) = 1/111
T(34, 37) = 1/111
T(35, 37) = 1/111
T(36, 37) = 1/111