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Variant: interlocking melds.

§1 Introduction. In the basic version of Chattahoochee (§A3), a meld consists of cards in sequence by rank, all of the same suit, for example ♥QKA234.

Among the many variations mentioned on the home page is to allow a meld that is a sequence of cards by rank, but alternating between two suits (§C4b), for instance ♦T♣J♦Q♣K♦A♣2♦3. In this interlocking variant proposed on this page, these alternators would be the only melds allowed, meaning that a one-suit sequence would no longer be recognized (except in the trivial case of a one-card meld).

Because a meld cannot meaningfully alternate unless it has at least two cards, the one-zero scoring variation (§C4e) is recommended:

number of cards	point value		number of cards	point value		number of cards	point value
1	0		7	21		13	78
2	1		8	28		14	91
3	3		9	36		15	105
4	6		10	45		16	120
5	10		11	55		17	136
6	15		12	66		n	n × (n − 1) ÷ 2

In the one-zero plan, the one-card meld is still permitted, because it aids in going out. However, it is worth zero points.

For simplicity, the same table of points is used for melds and for the interlocks that will be defined later. The two-zero plan (not shown here) would also be satisfactory, but the one-zero is used for all the examples on this page.

With alternating-suit melds, rather than single-suit, players have more options about what to do, and it may be easier to form long melds. For example, consider the almost-meld ♦4_♦6. In the single-suit game it can be filled by only ♦5, but in the alternating-suit game it can be filled by any of ♣5, ♠5, and ♥5.

With the wealth of melding opportunities provided by interlocking melds, there is probably little need for wild cards. Nonetheless, a scoring method for the use of them is provided.

Many of the examples below require multiple packs.

§2 Overlaps. A player might have two melds whose ranks overlap. Below are examples of some configurations, where the suits of the cards are not indicated. A yellow background indicates the common region.

Meld 2a:	3	4	5	6	7	8	9			each meld continues on a different end
Meld 2b:				6	7	8	9	T	J

Meld 2c:	3	4	5	6	7	8	9	T	J	one meld continues on both ends
Meld 2d:				6	7	8	9

Meld 2e:	6	7	8	9	T	J	Q	one meld continues on one end
Meld 2f:	6	7	8	9

Meld 2g:	6	7	8	9	neither meld continues on either end
Meld 2h:	6	7	8	9

Meld 2i:	3	4	5	6			a one-card overlap can occur, but it will score zero points
Meld 2j:				6	7	8

Meld 2k:	6	the minimal case, also zero points
Meld 2l:	6

Meld 2m:	3	4	5	6	7	8	9	T	J	Q	K	A	2	3	4	5	6
a very long meld can overlap itself

§3 Interlocks. When there are two melds in the same pair of alternating suits, and they overlap, and the suits are out of phase in the overlap area, an interlock is formed, and this is what can earn points. "Out of phase" means that equal ranks have opposite suits.

An interlock is not a meld, but it earns bonus points which are calculated as the product of these two values:

• the length of the interlock;
• the number of points associated with a meld of that length.

Like any other points, these bonus points are subject to the multiplier.

Example with spades and diamonds:

Meld 3a:	♠3	♦4	♠5	♦6	♠7	♦8	♠9			meld points 21	interlock: length 4, points 4 × 6 = 24
Meld 3b:				♠6	♦7	♠8	♦9	♠T	♦J	meld points 15

One meld can overlap two other melds, yielding two independent interlocks. The overlap areas might be the same, or different; and if different, might be conjoint or disjoint. Conjoint example:

Meld 3c:				♠7	♦8	♠9	♦T	♠J	♦Q	meld points 15
Meld 3d:			♠6	♦7	♠8	♦9	♠T			meld points 10
Meld 3e:	♦4	♠5	♦6	♠7	♦8					meld points 10
interlock 3c-3d: ranks 7-8-9-T length 4 points 4 × 6 = 24 interlock 3d-3e: ranks 6-7-8 length 3 points 3 × 3 = 9

There is no interlock between melds 3c and 3e because they are in phase.

Disjoint example, demonstrating the possibility of three independent interlocks with three melds:

Meld 3f:	♦4	♠5	♦6	♠7	♦8	♠9													meld points 15
Meld 3g:				♦7	♠8	♦9	♠T	♦J	♠Q	♦K	♠A	♦2	♠3	♦4	♠5	♦6			meld points 78
Meld 3h:														♠4	♦5	♠6	♦7	♠8	meld points 10
interlock 3f-3g: ranks 7-8-9 length 3 points 3 × 3 = 9 interlock 3g-3h: ranks 4-5-6 length 3 points 3 × 3 = 9 interlock 3f-3h: ranks 4-5-6-7-8 length 5 points 5 × 10 = 50

With four melds, four independent interlocks are possible:

Meld 3i:		♥6	♦7	♥8	♦9	♥T	♦J	meld points 15
Meld 3j:	♥5	♦6	♥7	♦8	♥9	♦T		meld points 15
Meld 3k:	♦5	♥6	♦7	♥8	♦9	♥T	♦J	meld points 21
Meld 3l:			♥7	♦8	♥9	♦T		meld points 6
interlock 3i-3j: ranks 6-7-8-9-T length 5 points 5 × 10 = 50 interlock 3j-3k: ranks 5-6-7-8-9-T length 6 points 6 × 15 = 90 interlock 3k-3l: ranks 7-8-9-T length 4 points 4 × 6 = 24 interlock 3l-3i: ranks 7-8-9-T length 4 points 4 × 6 = 24

When the number of ranks is odd, a meld can be self-interlocking:

Meld 3m:	♠3	♦4	♠5	♦6	♠7	♦8	♠9	♦T	♠J	♦Q	♠K	♦A	♠2	♦3	♠4	♦5	♠6
meld points 136, interlock points 4 × 6 = 24

When the number of ranks is odd, and at least two packs are used, a meld can be twice self-interlocking:

Meld 3n:	♠3	♦4	♠5	♦6	♠7	♦8 … ♦A	♠2	♦3	♠4	♦5	♠6	♦7	♠8 … ♠A	♦2	♠3	♦4	♠5	♦6
meld points 435; two interlocks, points 4 × 6 = 24 each

Self-interlocking melds, which require great length, will be rare in practice.

§4 Non-interlocks. The following are NOT interlocks even though the individual melds are valid.

In the overlap area, the suits are in phase, not out of phase:

Meld 4a:	♠3	♦4	♠5	♦6	♠7	♦8	♠9			meld points 21	NOT an interlock
Meld 4b:				♦6	♠7	♦8	♠9	♦T	♠J	meld points 15

Meld 4c is in spades and diamonds, but 4d is in spades and hearts:

Meld 4c:	♠3	♦4	♠5	♦6	♠7	♦8	♠9			meld points 21	NOT an interlock
Meld 4d:				♠6	♥7	♠8	♥9	♠T	♥J	meld points 15

§5 Partnerships. In the partnership game, when a player goes out before partner:

• any interlock involving two of retiree's own melds should be scored;
• any interlock involving one or retiree's melds and one of partner's melds should be scored.

Any interlock that involves two of partner's melds will be scored when partner goes out.

§6 Wild cards. Recall that if wild cards (symbolized "w") are used in a meld, they should not be counted in figuring the length of the meld, as explained in §C1a.

Similarly, wild cards that appear in an overlap should reduce the point value of the interlock. Specifically, the number of wild cards in the overlap area should be subtracted from the length of the overlap to form its net length. If the net length is less than zero, the interlock will count zero.

The point value is then calculated as the product of these two values:

• the net length of the interlock;
• the number of points associated with a meld of that net length.

Filching wild cards from the melds of a retiree never affects the retiree's score for melds, interlocks, or anything else, because everything was settled at retirement time.

As a basis for demonstrating how wild cards affect scores, melds 6a-6b show an interlock with no wild cards:

Meld 6a:	♣8	♥9	♣T	♥J	♣Q	♥K	♣A	♥2	♣3			meld points 36	interlock: overlap length 6, net length 6, points 6 × 15 = 90
Meld 6b:				♣J	♥Q	♣K	♥A	♣2	♥3	♣4	♥5	meld points 28

Melds 6c-6d show an interlock with one wild card:

Meld 6c:	♣8	♥9	♣T	♥J	♣Q	w	♣A	♥2	♣3			meld points 28	interlock: net length 5, points 5 × 10 = 50
Meld 6d:				♣J	♥Q	♣K	♥A	♣2	♥3	♣4	♥5	meld points 28

The pattern of distributing the wild cards within the overlap makes no difference. Among melds 6e-6j, each pair of melds has two wild cards in the overlap area:

Meld 6e:	♣8	♥9	♣T	♥J	♣Q	w	♣A	♥2	♣3			meld points 28	interlock: net length 4, points 4 × 6 = 24
Meld 6f:				♣J	♥Q	♣K	♥A	w	♥3	♣4	♥5	meld points 21
Meld 6g:	♣8	♥9	♣T	♥J	♣Q	w	♣A	♥2	♣3			meld points 28	interlock: net length 4, points 4 × 6 = 24
Meld 6h:				♣J	♥Q	w	♥A	♣2	♥3	w	♥5	meld points 15
Meld 6i:	♣8	♥9	♣T	♥J	♣Q	♥K	♣A	♥2	♣3			meld points 36	interlock: net length 4, points 4 × 6 = 24
Meld 6j:				♣J	♥Q	w	♥A	♣2	w	♣4	♥5	meld points 28

§7 Three-meld interlocks. All the interlocks discussed so far employ exactly two melds. In a collection of more than two melds, two interlocks might share a meld, but the interlocks themselves remain independent.

To help establish a pattern, a template for two-meld interlocks is shown next, where "a" and "b" represent any two different suits:

Meld 7a:	3a	4b	5a	6b	7a	8b	9a
Meld 7b:			5b	6a	7b	8a	9b	Ta	Jb	Qa

Three-meld interlocks will now be introduced. The basis for generalization:

1. Each meld is alternating in suit.
2. At each position of the overlap, no two melds have the same suit.
3. The total number of suits equals the number of melds.
4. If any one meld is removed, the entire interlock is gone, as the remaining melds do not form an interlock of their own. (Compare Borromean rings.)
5. No card is repeated within the interlock, unless it is very long.

As the for last point, a card can be repeated only if the length of the interlock exceeds the number of ranks in the pack. This will rarely happen.

The point value for a three-meld interlock is calculated as the product of these three values:

• the number 3 (which players might want to adjust);
• the net length of the interlock;
• the number of points associated with a meld of that net length.

As before, the net length is the overlap length minus the number of wild cards.

Here is a template for the three-meld interlock. Here, "e" represents a third suit (letters "c" and "d" are skipped because they might suggest clubs and diamonds):

Meld 7c:	3a	4b	5a	6b	7a	8b	9a
Meld 7d:			5b	6e	7b	8e	9b	Te	Jb	Qe
Meld 7e:		4a	5e	6a	7e	8a	9e	Ta

All five points of the "basis for generalization" remain in effect.

Here the template is filled in with actual suits ("a" = spades, "b" = hearts, "e" = diamonds):

Meld 7f:	♠3	♥4	♠5	♥6	♠7	♥8	♠9				meld points 21	interlock: overlap length 5, net length 5, points 3 × 5 × 10 = 150
Meld 7g:			♥5	♦6	♥7	♦8	♥9	♦T	♥J	♦Q	meld points 28
Meld 7h:		♠4	♦5	♠6	♦7	♠8	♦9	♠T			meld points 21

Example with two wild cards:

Meld 7i:	♠3	♥4	w	♥6	♠7	♥8	♠9				meld points 15	interlock: overlap length 5, net length 3, points 3 × 3 × 3 = 27
Meld 7j:			♥5	♦6	♥7	♦8	w	♦T	♥J	♦Q	meld points 21
Meld 7k:		♠4	♦5	♠6	♦7	♠8	♦9	♠T			meld points 21

§8 Four-meld interlocks. These are entirely analogous to the two- and three-meld interlocks. The following template corresponds to template 7a-7b, and to template 7c-7d-7e. Here, the fourth suit is represented by "f".

Meld 8a:	3a	4b	5a	6b	7a	8b	9a
Meld 8b:			5b	6e	7b	8e	9b	Te	Jb	Qe
Meld 8c:		4f	5e	6f	7e	8f	9e	Tf
Meld 8d:		4a	5f	6a	7f	8a	9f	Ta	Jf

All five points of the "basis for generalization" remain in effect.

The point value is calculated as the product of these three values:

• the number 12 (which players might want to adjust);
• the net length of the interlock;
• the number of points associated with a meld of that net length.

Here it is with actual suits filled in ("a" = spades, "b" = hearts, "e" = diamonds, "f" = clubs):

Meld 8e:	♠3	♥4	♠5	♥6	♠7	♥8	♠9				meld points 21	interlock: overlap length 5, net length 5, points = 12 × 5 × 10 = 600
Meld 8f:			♥5	♦6	♥7	♦8	♥9	♦T	♥J	♦Q	meld points 28
Meld 8g:		♣4	♦5	♣6	♦7	♣8	♦9	♣T			meld points 21
Meld 8h:		♠4	♣5	♠6	♣7	♠8	♣9	♠T	♣J		meld points 28

The same, except two wild cards:

Meld 8i:	♠3	♥4	♠5	♥6	♠7	♥8	♠9				meld points 21	interlock: overlap length 5, net length 3, points = 12 × 3 × 3 = 108
Meld 8j:			♥5	♦6	♥7	w	♥9	♦T	♥J	♦Q	meld points 28
Meld 8k:		♣4	♦5	w	♦7	♣8	♦9	♣T			meld points 21
Meld 8l:		♠4	♣5	♠6	♣7	♠8	♣9	♠T	♣J		meld points 28

An option mentioned on the main page is to award a bonus when a player's melds include four cards of the same rank, in four different suits. That would apply here, making four-card interlocks even more valuable.

Should the players have a pack with five or more suits, the pattern can be continued.

§9 Rationales. Mentioned above is that a meld cannot be genuinely alternating unless it contains at least two cards. Thus a one-card meld ought to be worth zero points.

Here is a technical reason for awarding zero points for an interlock of length one. Melds 9a and 9b do not interlock because 9a has clubs and hearts, but 9b has clubs and diamonds:

Meld 9a:	♣Q	♥K	♣A	♥2	♣3	meld points 10	NOT an interlock
Meld 9b:	♦Q	♣K	♦A	♣2	♦3	meld points 10

A player might assert that each should be interpreted not as one meld of five cards, but rather as five melds of one card each. In other words, the attempt is not to form one interlock five cards long, but rather to form five interlocks each one card long:

Group 9c:	♣Q		♥K		♣A		♥2		♣3	meld points 5 × 0	five interlocks: each length 1, points 5 × 0	a bad idea, even if legal
Group 9d:	♦Q		♣K		♦A		♣2		♦3	meld points 5 × 0

This will score a total of zero points, so a player will not bother trying it. To determine whether such a five-way split of a pre-existing meld would even be legal necessitates an examination of the intent of the rearrangement prohibition of §B1c. However, using the one-zero (or two-zero) point schedule forestalls the need for such deliberation.