Introduction

Background

Tachyon is an implementation of a constraint-based model for representing and reasoning about qualitative and quantitative aspects of time. Tachyon's data model is designed to provide substantial expressiveness and fast computation over convex intervals. Tachyon is serving as a testbed for topology-driven techniques for handling calculations over non-convex intervals. Our implementation of this model features a graphical interface using X-Windows and InterViews. We are currently exploring the use of Tachyon in a number of areas, including scheduling, project planning, feasibility analysis, and spatio-temporal data management. While we provide some information about Tachyon's underlying model and its algorithmic structure, communicating this is not our main focus in this document. The interested reader is referred to [1,2,3].

Most users of Tachyon will use its graphical user interface to:

• Create a network of events and constraints.
• Automatically layout the network.
• Add, modify, move and delete events and constraints.
• Cut and paste events and constraints.
• Solve the network.
• Print the graphical network to a postscript printer.

While it is not required that one use Tachyon's graphical user interface (batch and embedded versions are also useful, especially when interacting with another software tool), it does provide ease of use for stand-alone applications and for analysis of data produced in embedded applications of Tachyon. Thus the main focus of this manual will be on using Tachyon in the version that provides a graphical user interface.

About This Manual

This documentation describes how to install Tachyon and how to use the Tachyon graphical user interface and support utilities to develop temporal constraint networks. There are two parts to this manual.

Part 1, ``Getting Started,'' helps you install Tachyon, become familiar with the Tachyon graphical user interface, and understand the general roles and relationships of the main Tachyon tools. It contains the following chapters:

• Chapter 2 describes how to install Tachyon. It also provides the basic configuration and system requirements for Tachyon.

• Chapter 3 gives you a quick guide through building and running a sample network. You can use this chapter to verify that your installation is working and to become familiar with Tachyon.

• Chapter 4 provides a quick reference guide to the Tachyon features. It contains several tables listing menu commands and common procedures associated with them, toolbar buttons, and shortcut keys.

Part 2, ``Using Tachyon,'' provides the detailed information and procedures to help you use Tachyon. It contains the following chapters:

• Chapter 5 describes how to use the editor to create, edit or move events and constraints. It also provides detailed information on the Time Line Tool.

• Chapter 6 describes the configuration resource file and how to modify it to personalize your version of Tachyon.

• Chapter 7 details the file output produced by Tachyon and also describes the use and uses of the Tachyon Batch Utility.

• Chapter 8 discusses the enhancements which are currently being developed for future releases of Tachyon.

Notational Conventions Used

This manual uses the following words, abbreviations and typographic conventions:

-oo

Negative infinity.

+oo

Positive infinity.

e

Epsilon. The smallest period of time. In Tachyon, 1 second.

``argument''

Quotation marks enclose a new term the first time it is defined in text.

Constraint

A condition that exists between two events. In Tachyon, a constraint is also synonymous with ``edge''.

Edge

A constraint placed between two nodes, represented as an arrow in the Tachyon GUI. See Constraint.

Event

An activity which takes place over a period of time. In Tachyon, an event is synonymous with ``node''.

GUI

Graphical user interface.

MB

Mouse button.

Node

An event represented as a rectangular region in the Tachyon GUI. See Event.

SHIFT+LEFT MB

Small capital letters are used to indicate the names of the keys on the keyboard or mouse buttons. When you see a plus sign (+) between two key names, you should hold down the first key while pressing the second.

KP

Key Pad.

Support

Tachyon is a prototype tool, under constant development. While we have released versions of the software for evaluation and experimentation, it is not a commercially supported product at this time. Despite this, GE CRD tries to provide support to everyone using the Tachyon prototype.

If you have questions about Tachyon, one of the following resources may help you find an answer:

• The index in the product documentation and other printed product documentation.

• Online Help available from the help menu (little of this is currently available.)
• E-mail help, send a note to one of the following: farleyja@crd.ge.com, arthurr@crd.ge.com, or stillman@crd.ge.com
• For telephone help, call Jim at (518) 387-6513, Rick at (518) 387-6823 or Jon at (518) 387-5257 Monday through Friday, between 9:00 AM and 5:00 PM EST.