Explain the structure of well formed formulae, Database Management System

Assignment Help:

Explain the structure of well formed formulae in relational calculus.

Ans: a. An atom is a formula

b. If P1 is a formula, after that so are ¬P1 and (P1)

c. If P1 and P2 are formulae, after that so are P1 V P2, P1 ^ P2, P1 → P2

 d. If P1(s) is a formula containing a free variable s and r is a relation after that

       ∃ s ε r (P1(s) )  and ∀ s ε r (P1(s)) are also formulae


Related Discussions:- Explain the structure of well formed formulae

Checkpoint, what is check point in database management system

what is check point in database management system

Describe a technique for direct search, Describe a technique for direct sea...

Describe a technique for direct search? Explain how data is stored within a file so which direct searching can be performed. For a file of unordered fixed length records by u

Entity set that does not have sufficient attributes known as, An entity set...

An entity set that does not have sufficient attributes to form a primary key is called? An entity set that doesn't have sufficient attribute to form a primary key is known as w

What are the benefits of document scanning, What are the benefits of docume...

What are the benefits of document scanning? Document scanning, in addition to being cost-efficient, also enhances productivity. This service enhances security as you set the pa

Describe the algorithm for updating indices, Describe the algorithm for upd...

Describe the algorithm for updating indices for a single level index when a record is    (i) Inserted  (ii)  deleted What will be the modification if there are multilevel in

The proliferation of object-oriented methods, The Proliferation of Object-O...

The Proliferation of Object-Oriented Methods The first few years of the 1990s saw blossoming of around fifty various object oriented methods. This proliferation is a sign of g

Properties of a transaction , Properties of a Transaction        A tra...

Properties of a Transaction        A transaction has four main properties. These are: Atomicity Consistency Isolation or Independence Durability or Permanen

Discuss the problem of spurious tuples, Discuss the problem of Spurious tup...

Discuss the problem of Spurious tuples and how we may prevent it.    Ans:  A spurious tuple is, mainly, a record in a database that gets created while two tables are joined bad

Describe interfaces for the dba, Describe Interfaces for the DBA? Inte...

Describe Interfaces for the DBA? Interfaces for the DBA - Most database systems holds privileged commands which could be used only through the DBA's staff. These involves com

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd