Guessers

Guessers are agents or systems that attempt to determine an unknown value, state, or object by making successive guesses informed by partial information, prior knowledge, or statistical models. In information theory and cryptography, a guessing strategy orders possible candidates by their likelihood and continues guessing until the correct one is found, with performance typically measured by the expected number of guesses or the probability of success within a fixed number of tries.

There are several types of guessers. Deterministic guessers follow a fixed rule or order of candidates, such as alphabetic ordering or a predefined prior. Probabilistic guessers use randomness as part of their strategy, which can reduce worst-case time or improve adaptability to new information. Brute-force guessers systematically enumerate candidates, while heuristic guessers prioritize likely candidates based on patterns, rules, or learned models.

Guessers appear in various domains. In human problem solving and games, players act as guessers, as in 20 questions or charades. In computing, guessers include search, optimization, and constraint-satisfaction algorithms that propose candidates and adjust based on feedback. In security, guessers are involved in password cracking or credential guessing, leading to defenses such as rate limiting, salting, and stronger entropy requirements.

Evaluation of guessers focuses on metrics such as the average number of guesses to success, the probability of success within a given number of tries, and the computational or time cost involved. Effectiveness depends on information availability, the accuracy of underlying assumptions about distributions, and the nature of feedback received after each guess.