# What is BBN model?

## What is BBN model?

Bayesian Belief Network (BBN) is a Probabilistic Graphical Model (PGM) that represents a set of variables and their conditional dependencies via a Directed Acyclic Graph (DAG). To understand what this means, let’s draw a DAG and analyze the relationship between different nodes.

**What is forward/backward algorithm in hmm?**

The forward–backward algorithm is an inference algorithm for hidden Markov models which computes the posterior marginals of all hidden state variables given a sequence of observations/emissions , i.e. it computes, for all hidden state variables , the distribution. .

**What is the forwarding algorithm?**

A routing algorithm is a procedure that lays down the route or path to transfer data packets from source to the destination. They help in directing Internet traffic efficiently. After a data packet leaves its source, it can choose among the many different paths to reach its destination.

### What is BBN AI?

Bayesian belief network is key computer technology for dealing with probabilistic events and to solve a problem which has uncertainty.

**What is the probability of alarm ringing due to earthquake?**

if there is a burglary and an earthquake, the alarm rings with probability 0.9; if there is only a burglary, it rings with probability 0.8; if there is only an earthquake, it rings with probability 0.1; if there is neither a burglary nor an earthquake, the alarm doesn’t ring.

**What is forward and backward?**

If someone or something moves backward and forward, they move repeatedly first in one direction and then in the opposite direction.

#### What is posterior decoding?

More formally, instead of identifying a single path of maximum likelihood, posterior decoding considers the probability of any path lying in state k at time t given all of the observed characters, i.e. P(πt = k|x1,…,xn).

**Which routing algorithm is best?**

which is the best routing algorithm in networks?

- Distance-vector algorithm — Ex: RIP.
- link-state algorithm — Ex: OSPF.
- hybrid algorithm — Ex:EIGP.

**What is adaptive and non adaptive routing?**

Adaptive routing algorithms make routing decisions dynamically depending on the network conditions. Non-adaptive routing algorithms do not change the selected routing decisions for transferring data packets from the source to the destination.

## What are the important features of Bayesian belief networks BBN )?

Bayesian Belief Network is a graphical representation of different probabilistic relationships among random variables in a particular set. It is a classifier with no dependency on attributes i.e it is condition independent.

**What is the probability of the event that the alarm has sounded but neither a burglary nor an earthquake has occurred and John Call and Mary didn’t call?**

If both Mary and John call, the probability is ~50%. unless … Burglary is so unlikely that, if only Mary calls or only John calls, the probability of a burglary is still only about 5%. If both Mary and John call, the probability is ~50%.

**Are the burglary and earthquake random variables independent of each other?**

Burglar and Earthquake are independent a priori, but dependent given Alarm. (This is known as ‘explaining away.

### What is the goal of the forward-backward algorithm?

The goal of the forward-backward algorithm is to nd the conditional distribution over hidden states given the data. In order to specify an HMM, we need three pieces: Figure 2: A visualization of the forward and backward messages.

**Is it possible to do a backward algorithm in Python?**

You can do the same in python too. Backward Algorithm is the time-reversed version of the Forward Algorithm. In Backward Algorithm we need to find the probability that the machine will be in hidden state si s i at time step t and will generate the remaining part of the sequence of the visible symbol V T V T.

**What are inside-outside and forward-backward algorithms in EMNLP?**

Inside-outside and forward-backward algorithms are just backprop. InStructured Prediction Workshop at EMNLP. Rabiner, L. R. (1989). A tutorial on hidden markov models and selected applications in speech recognition.

#### Why is the forward algorithm more efficient than O (n2)?

In Forward Algorithm (as the name suggested), we will use the computed probability on current time step to derive the probability of the next time step. Hence the it is computationally more efficient O(N2.