关煞位河牌四加注彩虹面（CO River 4-Bet Rainbow）

Concept Breakdown

• CO (Cutoff): The position to the right of the button, generally considered one of the more advantageous positions. Acting order is before the button and after the dealer.
• River: The fifth and final community card; the betting round after this card is the river round.
• 4-Bet: The fourth raise. In the default context, the first preflop raise is called "open," the second raise is "3-bet," the third is "4-bet," and so on. The river betting structure is similar, but terms like "bet/raise/reraise/cap" are more common; the fourth raise can be considered a "4-bet."
• Rainbow: A board where all community cards are of different suits (i.e., three or four distinct suits), reducing the possibility of a flush draw.

Practical Meaning

"CO River 4-Bet Rainbow" describes a hand where the fourth raise occurs on the river, the player is in the CO position, and the board is rainbow. This term is often used to discuss extreme ranges and hand strength confrontations:

• A fourth raise on the river from the CO usually indicates a very strong hand (e.g., the nuts or second nuts), since high-level raises on the river typically only retain the most premium value range.
• A rainbow board means no flush is possible, so the opponent's raises are more concentrated on made hands or bluffs; flush draws are eliminated.
• This term is rarely seen in actual gameplay and is more common in teaching examples or strategic analysis, illustrating range polarization in a specific scenario.

Notes

• Using "4-bet" on the river is not as standardized as preflop; some players may simply call it a "reraise" or "cap."
• "CO River 4-Bet Rainbow" is not a standard fixed term but a combination of several independent concepts.