A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

P versus NP and other resource-bounded computation.
Questions regarding well-defined instructions for completing a task, and relevant analysis in terms of time/memory/etc.
Reference-request is used when the author needs to know about work related to the question.
Graph theory is the study of graphs, mathematical structures used to model pairwise relations between objects.
Algorithms on graphs, excluding heuristics.
Questions related to combinatorics and discrete mathematical structures
622 questions
Questions related to NP-hardness and NP-completeness.
621 questions
Computational complexity classes and their relations
596 questions
Computational and mathematical logic.
489 questions
Questions about approximation algorithms.
438 questions
formal languages, grammars, automata theory
406 questions
A soft question is a question (possibly subjective) about the field of theoretical computer science as opposed to being a question in theoretical computer science.
392 questions
general questions about selecting a best element from some set of available alternatives.
389 questions
Quantum computation and computational issues related to quantum mechanics
369 questions
Automata Theory, including abstract machines, grammars, parsing, grammatical inference, transducers, and finite-state techniques
368 questions
Computability theory a.k.a. recursion theory.
354 questions
Circuit complexity is the study of resource-bounded circuits and the functions computed by such circuits.
346 questions
Programming languages, in particular, focussing on their semantics.
341 questions
Type structure is a syntactic discipline for enforcing levels of abstraction.
Time complexity of decision problems or relations among time-bounded complexity classes. (Use the [analysis-of-algorithms] tag for the time taken by particular algorithms.)
337 questions
Properties and applications of data structures, such as space lower bounds, or time complexity of insertion and deletion of objects.
328 questions
Theoretical questions about Machine learning, especially Computational Learning Theory, including Algorithmic Learning Theory, PAC learning, and Bayesian Inference
320 questions
SAT stands for the Boolean satisfiability problem.
288 questions
Computational Geometry is the study of geometric problems from a computational perspective. Examples of problems include: computation of geometric objects such as convex hulls, dimensionality reductio…
264 questions
Theoretical aspects of cryptography and information security.
255 questions
questions about lowerbounds on functions, usually the complexity of an algorithm or a problem
250 questions
How hard is counting the number of solutions?
237 questions
Church's formal system used in computatability, programming languages and proof theory to represent effective functions, programs and their computation, and proofs.
229 questions
Questions in probability theory
208 questions
Linear algebra deals with vector spaces and linear transformations.
203 questions
The Turing machine is a fundamental model of computation, especially in theoretical work.
199 questions
Questions about Boolean functions and their analysis
194 questions
An algorithm whose behaviour is determined by its input and a generator producing uniformly random numbers.
191 questions
Mathematical and computational method for finding the best outcome in a given mathematical model where the list of requirements is represented as linear relationships.
187 questions
The big picture tag is for a "broad, overall view or perspective of an issue or problem."
185 questions
Machine learning and learning theory: PAC learning, algorithmic learning theory, and computational aspects of Bayesian inference and graphical models.
180 questions
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