Poker is a complex game that requires a player to make strategic decisions based on various factors such as the cards in their hand, the actions of their opponents, and the betting patterns of the game. However, there is one rule in particular that can be used as a guide to help make the best decisions, and that is Pinnock’s Razor. This rule, also known as the 50% Rule, is an important concept for all players to understand in order to succeed at the poker table.
What is Pinnock’s Razor?
Pinnock’s Razor is a principle that states that in a heads-up pot, on any street, the out-of-position player (OOP) should attempt to construct their strategy in such a way as to force the in-position player (IP) to bet or raise at most 50% of the time. When fully utilized, Pinnock’s Razor allows for quick hand analysis in many different spots, and it allows for proper range construction in situations that are difficult for humans to understand. It applies only to the analysis of the equilibrium, and it applies most strongly to River situations with the stack larger than the pot. However, it does not apply when the stack is smaller than the pot.
How the 50% Rule Applies to Poker
The 50% Rule applies to most Preflop, Flop and Turn situations and it applies to SRP, 3BP, 4BP, limped, etc. It can have significant consequences for the way that players construct their ranges and make decisions. For example, the OOP should attempt to ensure that their checking range is strong enough that IP should check back at least 50% of the time. If the OOP does not have enough strong hands in their range to prevent IP from betting more than 50% of the time when OOP checks, then OOP should check their entire range.
If the OOP has a betting range, and if OOP checks, then IP should check back more than 50% of their range. This applies in any spot regardless of who the preflop raiser (PFR) was. For example, when the big blind (BB) is up against the button (BU) on boards where BU bets more than 50% of the time, the BB has to check 100%. Similarly, when the small blind (SB) is up against the BB, and the SB checks, the BB has to check back more than 50% of the time since the SB has a leading range.
For simulations when IP bets more than 50% of the time it is ok to remove the donking line. In spots where the IP preferred bet size is smaller than the OOP preferred bet size, the 50% rule will often not apply on the flop and turn but will still apply on the river (because IP will almost always bet bigger than OOP on the river). This is because the spots where the IP bets smaller than OOP are the spots where equity denial dominates the IP strategy.
When IP is betting more frequently, OOP is incentivized to check more with strong hands and bet more with weaker ones (like flush draws). So when we are IP and facing a check in a give-up spot (like when OOP c/r turn and checks river) we should use the 50% rule to build our range. We check the middle 50% of our range, bluff the bottom ⅙ and value bet the top ⅓ (if we are betting pot, the ratio will be different for a different bet size and when we use multiple bet sizes and so on).
The existence of donking ranges on turn and river at equilibrium is a direct consequence of the 50% rule. In other words, if OOP is not building a donking range when it should, IP should respond with a lot more checking back than at equilibrium. This is why the delay c-bet works so well against the double check as weak players often fail to protect the double-check bet to a very extreme degree.
Another important aspect of Pinnock’s Razor is the exploitation of opponents who are not following the 50% rule. If the OOP is not following the rule, the IP does not have to follow it either. For example, if the villain only has give-ups when he checks, the IP should bet everything. Similarly, if the villain is not betting enough when checked to then OOP should bet all of its strong hands and play an unprotected checking range.
The Limitations of Pinnock’s Razor
When the stack-to-pot ratio (SPR) is so small that the stack left to bet is smaller than the pot, the 50% rule does not apply, and the OOP should just bet all of its strong hands. In turn, when OOP checks here their range is extremely weak, and IP gets to bet a ton if not all of its range vs this check. Basically, when the SPR < 1 the IP can bet more than 50% in order to make the OOP’s strong hands indifferent between betting and checking.
Important to note that the 50% rule does not always apply in every situation. For example, it does not apply on the river when the board is a chop (straight on board). Additionally, it does not apply when the stack is smaller than the pot. This is because when the stack-to-pot ratio (SPR) is less than 1, the IP can bet more than 50% in order to make the OOP’s strong hands indifferent between betting and checking. In these situations, the OOP should just bet all of its strong hands.
In conclusion, Pinnock’s Razor is a powerful strategy that can be used in no-limit games and heads-up pots. It allows for quick hand analysis and proper range construction in difficult situations. It applies most strongly to River situations with the stack larger than the pot. However, it is important to note that it does not apply in every situation and should be used in conjunction with other strategies and considerations. Additionally, it is important to be aware of how opponents may be exploiting or not following the 50% rule and adjust accordingly.