Half Combination: Two Branches in a Three Harmony Frame

Half combination, or 半合, is a structural concept in Chinese metaphysics used when only two of the three branches of a three-harmony combination are present. It is not a complete combination, but it is also not inert: the two present branches create a directional pull toward the missing third branch. The term belongs to the vocabulary of branch relationships, and it is often discussed alongside arch combination, arch meeting, and hidden combination because these four categories are easily confused. They all involve incomplete or indirect branch interaction, but they differ in what is absent and where the interaction is located.

四个名称容易混用

The four terms 半合，拱合，拱会, and 暗合 are frequently mixed up because all of them describe situations in which a full combination is not formed. A half combination refers to two of the three branches of a three-harmony combination appearing together. An arch combination refers to the first and last branches of a three-harmony combination appearing in adjacent pillars while the middle branch is absent. An arch meeting refers to the first and last branches of a three-meeting direction appearing in adjacent pillars while the middle branch is absent. A hidden combination refers to combination occurring at the level of hidden stems rather than between the branches themselves. In all four cases, the result is not a complete combination. The distinction lies in what is missing: the half combination lacks one branch; the arch combination and arch meeting lack the middle branch and require adjacency; the hidden combination is located in the hidden-stem layer.

半合：三支到了两支

A half combination is an incomplete three-harmony combination. In a three-harmony combination, three specific branches form one complete unit, such as 申子辰 forming water, 亥卯未 forming wood, 寅午戌 forming fire, or 巳酉丑 forming metal. When only two of the three branches appear, the configuration is called a half combination. It is stronger than a single branch standing alone, because the two present branches produce a directional attraction toward the missing branch, but it is weaker than the full three-harmony combination. The two branches are not treated as having completed the transformation; they are treated as showing a tendency or a pull in a particular elemental direction.

Within a half combination, there is a further distinction based on which two branches are present. If one of the two branches is the peak branch of the three-harmony group — that is, one of 子，午，卯, or 酉 — then the half combination is generally considered stronger than a half combination formed without that peak branch. For example, in the 申子辰 water group, 子 is the peak branch. A half combination of 申 and 子, or 子 and 辰, has more force than a half combination of 申 and 辰. The presence of the peak branch gives the incomplete structure a clearer center of orientation.

A half combination can become a full combination when the missing branch is supplied later. This later supply may come from a luck cycle, an annual cycle, or another relevant time layer. If the missing branch arrives in such a cycle, the previously incomplete structure can be read as a complete three-harmony combination for that period. Before that point, however, the half combination only indicates that a given elemental direction has been pulled up or activated. It should not be written or interpreted as a full three-harmony combination. The third branch, the month command, and the relevant luck or annual cycles all need to be considered before a full combination can be recognized.

拱合与拱会：中间那一支缺席

An arch combination occurs when the first and last branches of a three-harmony combination appear in two adjacent pillars while the middle branch does not appear. For example, 申 and 辰 are the first and last branches of the 申子辰 water group. If 申 and 辰 appear in adjacent pillars and 子 is absent, this is described as 申辰拱子, meaning that 申 and 辰 arch toward 子. The absent middle branch is the peak branch of the three-harmony group, and the two outer branches are said to frame or enclose it.

An arch meeting is the analogous structure for a three-meeting direction. A three-meeting direction consists of three consecutive seasonal branches, such as 寅卯辰 for wood in spring, 巳午未 for fire in summer, 申酉戌 for metal in autumn, or 亥子丑 for water in winter. If the first and last branches of such a group appear in adjacent pillars while the middle branch is absent, the configuration is called an arch meeting. For example, 寅 and 辰 appearing in adjacent pillars with 卯 absent is described as 寅辰拱卯, meaning that 寅 and 辰 arch toward 卯.

Arch combination and arch meeting are only checked between three pairs of adjacent pillars: the year pillar and the month pillar, the month pillar and the day pillar, and the day pillar and the hour pillar. If the two branches appear in non-adjacent pillars, the arch structure is not considered to be formed. On this site, the engine marks the transformation status of both arch combination and arch meeting as no. That means neither is treated as a completed transformation. The absent middle branch is not treated as if it were actually present, and no combination transformation is recorded.

暗合：合在藏干这一层

A hidden combination is a combination that takes place between the hidden stems stored within earthly branches, rather than between the branches themselves. Each earthly branch contains one or more hidden stems, and those hidden stems can enter into stem-level combinations with hidden stems in other branches. When such a combination occurs, the branches themselves are not directly combining. The interaction is located one layer down, in the hidden stems.

This differs from a half combination, where the relationship is between the branches as branch structures belonging to a three-harmony group. It also differs from an arch combination or arch meeting, where the relationship is between outer branches framing an absent middle branch. In a hidden combination, the visible branch pair may show no obvious branch-level combination at all, but the hidden stems inside them form a stem combination. The term 暗合 points to this concealed or indirect character.

四者在判定上的分别

The common point among half combination, arch combination, arch meeting, and hidden combination is that none of them constitutes a complete combination. In each case, a full three-harmony or three-meeting structure is not present. The differences lie in what is missing and at what layer the interaction occurs.

A half combination lacks one branch of a three-harmony group. The two present branches may or may not include the peak branch. It creates a directional pull, but it remains incomplete. An arch combination lacks the middle branch of a three-harmony group, and the two outer branches must be in adjacent pillars. An arch meeting lacks the middle branch of a three-meeting direction, and likewise requires the two outer branches to be in adjacent pillars. A hidden combination does not operate at the branch level at all; it operates at the level of hidden stems stored within the branches.

In judgment, a half combination can only be said to show that a certain elemental direction has been pulled up. It is not written as a full three-harmony combination until the missing third branch, the month command, and the relevant luck or annual cycles supply what is needed. If those conditions are not met, the half combination remains a directional tendency, stronger than an isolated branch but weaker than a complete combination. Arch combination and arch meeting are not marked as transformations on this site, and their absent middle branch is not treated as present. Hidden combination is recognized only at the hidden-stem layer and is not equated with a branch-level combination. These distinctions prevent the four categories from being collapsed into one another, even though all four describe incomplete or indirect interaction.