Co-tree

Co-tree
The branches of a graph which are not included in a tree form a co-tree. A co-tree is a complement of a tree.

Chords or Links
The branches of a co-tree are called links or chords. 

Tree

Tree
A tree of a connected graph is defined as a set of branches which are connected , contains no circuits, contains all nodes of the graph. In simple a tree connects all the nodes of the graph without forming a closed path.

Twigs
Branches of tree are called twigs.

Path

Path
It is a subgraph of a given graph, such that we can proceed from one node to the other by traversing the branches of the subgraph in a sequential manner.

Incident Branch

Incident Branch
A branch k is called incident to a node l if the node l is an end point of the branch k.

Subgraph

Subgraph
A subgraph of a graph is a subset of the branches of the graph.

Node

Node
The end point of a branch is called is a node. The number of nodes in a graph is denoted by n.

Branch

Branch
Each oriented line segment of the graph is called branch. The number of branches in a graph is denoted by b.

Mobile OS

Mobile OS 
OS for mobile handheld devices, wireless, devices,  palm PC, pocket PCs, PDAs and phones.

Protection mechanism

Protection mechanism
A mechanism at an OS  to protect against unauthorized accesses to the resources. 

Deregistering

DeRegistering
Making it unfeasible for the RTOS to schedule like a task.

Registering a Device

Registering a Device

Making it feasible for RTOS to schedule like a task.

Linux OS

Linux OS
A powerful operating system with UNIX like features plus special device driver scheduling features and memory management features.

Fixed real time scheduling

Fixed real time scheduling
A scheduling strategy in which the time for each task is fixed.

Critical section run

Critical section run
In spite of higher priority pending, a critical section is allowed to run by a scheduler using the semaphore.

Cooperative Scheduling

Cooperative Scheduling
A waiting task lets another task run till it finishes.

Time Slicing Scheduling

Time Slicing Scheduling
A scheduling algorithm in which each task is allotted a time slice after which it is blocked and waits for its turn on the next cycle. 

Preempting scheduling

Preempting scheduling
A scheduling algorithm in which  a higher priority task is forced to block by the scheduler to let a higher priority task run. 

Round Robin or Cyclic Scheduling

Round Robin or Cyclic Scheduling 
A scheduling algorithm in which the tasks are scheduled in a sequence from a list of ready tasks. 

Real Time Operating System

Real Time Operating System
Operating system with real time task scheduling, interrupt-latency control, synchronization of tasks with IPCs, predictable timing and synchronization behavior of the system.

Operating system

Operating system
A system having kernel functions, file management functions and other functions also.