Planning AI: Finding Solutions to Complex Problems

You may not have thought so until now, but planning is an important aspect of artificial intelligence (AI) that helps AI systems make smart decisions and achieve specific goals. Just like humans, they need to think ahead and consider the best course of action to solve problems.

Think of it as having an assistant guiding machines through complex problems in the most efficient way. From logistics to cybersecurity, these intelligent AI planning systems optimize workflows, allocate resources, and tackles challenges across diverse fields.

In this article, we will delve into this subset of AI power and explore how it works and the most common ways it is used in the real world.

Planning algorithms

Planning algorithms are computational techniques used to generate plans or sequences of actions to achieve specific goals. Machine learning techniques can be integrated into planning algorithms to enhance performance and adaptability. 

These algorithms analyze the problem domain with state space search, go through possible actions and states, and determine the optimal path or sequence of actions to reach the desired goal. 

Several algorithms are commonly used in planning AI, each with its own approach and characteristics. Some of the prominent planning algorithms include:

Forward state space planning (FSSP)

Forward state space planning is a methodical approach to solving problems by exploring the different states of the problem. It begins from the starting point and progresses towards the desired goal.

The algorithm creates new states by taking actions, with a focus on selecting those that bring users closer to the goal. This process continues until a path to the goal is established or until the entire state space is fully explored. It is particularly useful when dealing with uncertain or complex routes to the goal. 

However, it may encounter difficulties when dealing with large state spaces or constantly changing environments. Nevertheless, it is widely used in various fields, such as robotics, logistics, and video games.

Backward state space planning (BSSP)

This type of planning takes a reverse approach. Instead of starting from the initial state and progressing towards the goal, it begins from the goal state and traces the sequence of actions backward. 

In this planning process, the algorithm considers the preconditions of actions to determine the preceding states in reverse order until it reaches the initial state. By doing so, backward planning effectively handles uncertain or complex paths from the starting point to the goal.

Backward planning can face challenges when dealing with big or complex state spaces and environments that change over time. The sheer number of possible states and the need to handle real-time updates and changes can affect how well it performs.

Forward (progression) state-space searchBackward (regression) state-space search


Heuristic search

Heuristic search is a commonly used planning algorithm in AI. It relies on estimated measures or heuristics to help guide the search process and focus on more promising paths.

Instead of blindly exploring all possibilities, heuristic search evaluates states or actions based on their estimated potential for reaching the goal. This approach allows for efficient navigation through complex problem spaces.

One well-known heuristic search algorithm is A*. It considers the cost of actions and the estimated distance to the goal to prioritize exploration. Heuristic search is particularly useful in domains with large or intricate state spaces, as it enables efficient planning and decision-making.

Classical planning

Classical planning assumes a predictable and obvious environment. It generates plans using logical reasoning to guarantee the accomplishment of a goal. The problem is represented by initial and goal states, actions, and their respective requirements and outcomes.

The algorithm systematically explores actions and states, deducing the steps needed to find a workable and efficient plan. 

One well-known classical planning algorithm is STRIPS. It is suitable for domains with well-defined rules and characteristics, although it may face challenges when dealing with uncertainty.

Classical planning continues to be essential in deterministic problem domains, particularly in areas such as robotics and control systems.

Probalistic planning

In AI, probabilistic planning tackles situations with uncertainty and probabilistic outcomes. It considers the likelihood of actions leading to desired states and incorporates probability distributions.

The algorithm explores actions and states to achieve the desired outcome. It employs techniques like Markov Decision Processes (MDPs) or Partially Observable Markov Decision Processes (POMDPs) to model uncertainty. By evaluating probabilities and rewards, probabilistic planning strikes a balance between risk and potential reward.

Probabilistic planning finds practical applications in various fields, such as autonomous driving, healthcare, and finance. The computational complexity of reasoning about uncertainties can be a challenge. Nonetheless, probabilistic planning empowers informed decision-making in environments with uncertainty.

Planning domains

Planning domains in AI refers to the specific problem environments or domains in which planning algorithms operate. This kind of domain encompasses the set of possible states, actions, goals, and constraints that define the problem space.

Planning Domain Definition Language (PDDL) serves as a standardized language for representing planning problems and domains, which these algorithms can interpret and operate upon.

Domain-independent planning refers to the ability of planning algorithms and systems to operate across various problem domains without requiring specific knowledge or customization.

The definition of a planning domain typically involves specifying the following components:

Initial state

The initial state refers to the starting point of a planning problem or scenario. It represents the state of the environment or system at the beginning of the planning process.

It defines the conditions, properties, or variables (regression) that describe the state of the problem domain before any actions or operations have been performed. It serves as the foundation for generating plans and determining the sequence of actions needed to achieve the desired goals.

The initial state typically includes relevant information about the status of objects, locations, resources, or any other relevant entities in the problem domain. It provides the context from which the planning algorithm begins its exploration of the state space.


Actions refer to the operations or transformations that can be done to change the state of a problem domain during the planning process. They represent the available choices or steps that can be taken to move from one state to another in order to achieve the desired goals.

When generating plans, the planning algorithm evaluates the preconditions of available actions to determine which actions are applicable or can be executed in the current state. It then considers the effects of these actions to predict the resulting state after their execution. 

By examining the available actions, their preconditions, and their effects, the algorithm explores the space of possible actions and their consequences. 

It generates a sequence of actions that will transform the initial state into the desired goal state when executed in the appropriate order. Deep learning techniques can be used to learn action models that describe the effects of different actions in a planning domain.

State space

The state space refers to the collection or set of all possible states that a planning problem can inhabit. It represents the different configurations, conditions, or arrangements the problem domain can exhibit at any given time.

It encompasses the range of possible states that can be reached by applying actions or operations. It defines the boundaries and scope of the problem domain, providing a comprehensive view of the different states the system can transition between.

State space captures the relevant aspects or variables that define the state of the problem domain. These variables can include object locations, properties, resource availability, agent positions, or any other factors that are important in the context of the planning problem.

Search is performed in the state spaceState Space: V: set of states, E: set of transitionsBut: Computed graph is a subset of state spaceSearch modes: forward, backward



In planning AI, goals refer to the desired states, conditions, or objectives the planning algorithm aims to achieve. Goals define the specific outcomes, or end states, that planners strive to reach by generating plans and executing actions.

Goals in planning AI can be expressed in various forms, depending on the problem domain and the specific requirements. They can represent desired configurations of objects, target states of variables, constraints to satisfy, or objectives to optimize.

When formulating goals, planners typically specify the conditions or properties that need to be satisfied or achieved. These conditions can be based on the values of variables, the presence or absence of certain objects, or the fulfillment of specific constraints.

Advantages and drawbacks

Planning AI offers several advantages and drawbacks, which are important to consider when applying planning techniques in various domains. Here are some of the key points to consider:


  • Adaptability: Planning AI can adapt to dynamic and changing environments. It can generate plans that respond to new information, unexpected events, or evolving goals by reevaluating the state and generating updated plans.
  • Systematic and structured: Provides a systematic and structured approach to problem-solving. It analyzes the problem domain, explores the state space, and generates plans based on logical reasoning and algorithmic techniques.
  • Optimal solutions: Planning algorithms can find optimal or near-optimal solutions by searching the state space and evaluating the potential outcomes of actions. They aim to generate plans that minimize costs, maximize rewards, or satisfy specified objectives.
  • Decision-making: Planning tools can assist decision-making by evaluating different action sequences and their consequences. It provides insights into the feasibility, risks, and potential outcomes of different courses of action, helping in making informed decisions.
  • Complex problem solving: Can tackle complex problems involving multiple variables, dependencies, and constraints. It can handle large state spaces and consider various factors simultaneously, making it suitable for domains with intricate planning requirements


Computational power: Planning AI can face challenges in terms of computational complexity, especially when dealing with large state spaces or complex problem domains. Searching through the state space and evaluating actions can become computationally demanding, requiring efficient algorithms and optimizations.

Knowledge representation: It heavily relies on accurate and comprehensive knowledge representation. Constructing a precise problem domain model, including preconditions, effects, and action semantics, can be time-consuming and error-prone.

Uncertainty handling: Traditional planning approaches may struggle with handling uncertainty or probabilistic outcomes. Incorporating uncertainty into planning algorithms can be challenging, and specialized techniques like probabilistic or stochastic planning may be required.

Sensitivity to domain models: The effectiveness of planning AI is highly dependent on the quality of the domain model. If the model fails to capture all relevant aspects of the problem domain or contains inaccuracies, the generated plans may not be optimal or may even be infeasible.

Lacks responsiveness: Planning AI typically involves offline planning, where plans are generated before execution. This can limit its ability to respond rapidly to real-time changes or unforeseen events, requiring adaptations or replanning in dynamic environments.

Real-world use cases

The applications of planning AI are far-reaching and diverse; here are just a few examples of how this powerful, versatile tool is used in different ways.


Planning AI is a crucial component of robotics, enabling intelligent decision-making, autonomous behavior, and efficient task execution. It generates optimal, collision-free paths for robots to navigate in their environment. They can move efficiently by considering obstacles while minimizing travel time and energy consumption.


Scheduling and logistics

In scheduling and logistics, it optimizes the allocation of resources, minimizing costs and improving efficiency. Planning AI generates optimized routes for delivery vehicles, considering factors such as traffic conditions, scheduling problems, and vehicle capacities. This minimizes travel distances, reduces fuel consumption, and improves on-time delivery.

It also helps in optimizing inventory levels by analyzing demand patterns, lead times, and storage capacities. It helps with inventory replenishment by generating planning and scheduling guides to ensure optimal stock levels, reduce stockouts, and minimize holding costs.

Project management

Planning AI optimizes resource allocation by analyzing project requirements, resource availability, and skillsets. It generates plans that allocate resources effectively, minimizing bottlenecks and maximizing productivity. It also helps schedule project tasks based on dependencies, priorities, and pricing. 


Planning AI assists in incident response by providing real-time analysis of security incidents. It generates incident response plans that outline the necessary steps for containment, eradication, and recovery, enabling swift and effective responses to security breaches.

By leveraging planning AI in cybersecurity, organizations can enhance threat detection, automate incident response, fortify defenses, and stay ahead of evolving cyber threats. This enables a more proactive and effective approach to safeguarding critical systems and data.

To summarize

In conclusion, planning AI represents a cornerstone of AI research and application, empowering machines to autonomously generate plans and action sequences to tackle complex problems and achieve desired outcomes. 

With its diverse range of algorithms and applications, planning AI holds great promise for revolutionizing domains such as robotics, scheduling, logistics, and decision-making. 

Understanding the principles and methodologies of planning AI is essential in unlocking the potential of intelligent automation and advancing what we know of AI technology.

There are many subsets to AI that all work together to solve complex problems. To learn more about what AI can do and how it does it, stay tuned to our Top Apps blog.