Multinational Naive Bayes is the classic algorithm for text classification and NLP. For an instance, let’s assume a set of sentences are given which are belonging to a particular class. With new input sentence, each word is counted for its occurrence and is accounted for its commonality and each class is assigned a score. The highest scored class is the most likely to be associated with the input sentence.
It may be tempting to assume that users will perform procedural tasks one by one in a neat and orderly way. For example, in a procedural conversation flow using dialogs, the user will start at root dialog, invoke the new order dialog from there, and then invoke the product search dialog. Then the user will select a product and confirm, exiting the product search dialog, complete the order, exiting the new order dialog, and arrive back at the root dialog.
Using chatbot builder platforms. You can create a chatbot with the help of services providing all the necessary features and integrations. It can be a good choice for an in-house chatbot serving your team. This option is associated with some disadvantages, including the limited configuration and the dependence on the service. Some popular platforms for building chatbots are:
In a particularly alarming example of unexpected consequences, the bots soon began to devise their own language – in a sense. After being online for a short time, researchers discovered that their bots had begun to deviate significantly from pre-programmed conversational pathways and were responding to users (and each other) in an increasingly strange way, ultimately creating their own language without any human input.
Since 2016 when Facebook allows businesses to deliver automated customer support, e-commerce guidance, content and interactive experiences through chatbots, a large variety of chatbots for Facebook Messenger platform were developed. In 2016, Russia-based Tochka Bank launched the world's first Facebook bot for a range of financial services, in particularly including a possibility of making payments.  In July 2016, Barclays Africa also launched a Facebook chatbot, making it the first bank to do so in Africa. 
Chatbots have come a long way since then. They are built on AI technologies, including deep learning, natural language processing and machine learning algorithms, and require massive amounts of data. The more an end user interacts with the bot, the better voice recognition becomes at predicting what the appropriate response is when communicating with an end user.
Malicious chatbots are frequently used to fill chat rooms with spam and advertisements, by mimicking human behavior and conversations or to entice people into revealing personal information, such as bank account numbers. They are commonly found on Yahoo! Messenger, Windows Live Messenger, AOL Instant Messenger and other instant messaging protocols. There has also been a published report of a chatbot used in a fake personal ad on a dating service's website.
Rather than having the campaign speak for Einstein, we wanted Einstein to speak for himself, Layne Harris, 360i’s VP, Head of Innovation Technology, said to GeoMarketing. "We decided to pursue a conversational chatbot that would feel natural and speak as Einstein would. This provides a more intimate and immersive experience for users to really connect with him one on one and organically discover more content from the show."
A bot is software that is designed to automate the kinds of tasks you would usually do on your own, like making a dinner reservation, adding an appointment to your calendar or fetching and displaying information. The increasingly common form of bots, chatbots, simulate conversation. They often live inside messaging apps — or are at least designed to look that way — and it should feel like you’re chatting back and forth as you would with a human.
There is no one right answer to this question, as the best solution will depend upon the specifics of your scenario and how the user would reasonably expect the bot to respond. However, as your conversation complexity increases dialogs become harder to manage. For complex branchings situations, it may be easier to create your own flow of control logic to keep track of your user's conversation.
Oftentimes, brands have a passive approach to customer interactions. They only communicate with their audience once a consumer has contacted them first. A chatbot automatically sends a welcome notification when a person arrives on your website or social media profile making the user aware of your chatbots presence. This makes you seem more proactive, thus enhancing your brand's reputation and can even increase interactions, having a positive effect on your sales numbers, too.
1. AI-based: these ones really rely on training and are fairly complicated to set up. You train the chatbot to understand specific topics and tell your users which topics your chatbot can engage with. AI chatbots require all sorts of fall back and intent training. For example, let’s say you built a doctor chatbot (off the top of my head because I am working on one at the moment), it would have to understand that “i have a headache” and “got a headache” and “my head hurts” are the same intent. The user is free to engage and the chatbot has to pick things up.
Interface designers have come to appreciate that humans' readiness to interpret computer output as genuinely conversational—even when it is actually based on rather simple pattern-matching—can be exploited for useful purposes. Most people prefer to engage with programs that are human-like, and this gives chatbot-style techniques a potentially useful role in interactive systems that need to elicit information from users, as long as that information is relatively straightforward and falls into predictable categories. Thus, for example, online help systems can usefully employ chatbot techniques to identify the area of help that users require, potentially providing a "friendlier" interface than a more formal search or menu system. This sort of usage holds the prospect of moving chatbot technology from Weizenbaum's "shelf ... reserved for curios" to that marked "genuinely useful computational methods".