Addressing Limits

Organisational Layers

Most influences go

forward from strategy to

projects, but some

influences go backward

or sideways

Strategic

Assessment

Real Equipment

Why Pick On FPS?

An FPS is foundational – there is

high value in getting it right, and

having everyone read it the same

way

The language is formal and technical

Altering a few words is much easier

than rework of built equipment

A requirement can be verifiable yet incorrect; … a requirement

which has been overlooked. Mere analysis, inspection, or review

alone will find some of these issues but generally is far weaker

than usually is realized - Wikipedia

We can bring in experts

They can be familiar with what is

old, but they have the same limit

on what is new, and they can have

tunnel vision – the collaboration

task can become insurmountable

We can build a model of it

Building a model by hand will build up familiarity,

so what is new is reduced, but it will take a long

time and it will fixate on the spatial aspects, so it

doesn’t handle mistakes at the abstract level

early in the process

To keep the workload down, people filter out

what they don’t think is necessary – but they

have the same four pieces limit on working out

what is necessary

5. VEHICLE SUB-SYSTEM

5.1. Overview

5.1.1. The VSS shall comprise all SmartBus Equipment

mounted on or installed in the

SmartBus vehicle fleet.

5.1.2. A notional block diagram of the VSS is shown in Figure

3. The key VSS components are:

a. Bus Controller. This Equipment processes inputs from

the location sub-system,

inputs and outputs from the communications sub-system and

the on-board

Electronic Ticketing Machine (ETM). The Bus Controller

provides outputs to the

driver console and also to optional on-board passenger

information systems (both

announcement and display). Apart from the processor, the

Bus Controller

comprises:

(1) Location Sub-System. This includes the GPS receiver,

odometer pulses

and door sensor status (open or closed).

(2) Bus Communications. This enables radio

communications with the MSS.

b. Driver console. This Equipment displays Trip information

and on-time running

performance to the driver.

Automated Requirements Analysis

We are proposing the use of a system which takes

the text of a plan or specification and turns it into a

complete and accurate semantic working structure.

Documents as Machinery

3.2.4.3 Chapter 1, Space System Description. This chapter shall describe the space system and supporting facilities in sufficient detail to afford the reader a single source document of general system information. A brief narrative shall describe the purpose, main features and leading particulars for the space system as described below. Illustrations that clarify a particular system or reduce the verbiage necessary for explanation shall be included.

3.2.4.3.1 Description of the satellite. The description shall be of sufficient detail to provide an understanding of the purpose and function of the subsystems, their relation to overall system operation, and such additional information as to enable the crew member to understand subsystem functions peculiar to the satellite. Subsequent paragraphs shall describe in greater detail subsystems peculiar to that satellite. Such information shall include a general discussion of each major subsystem.

The goal is to have documents treated as just another piece of

machinery. Then we can have tools to tell us about:

• Things that are broken, not connected, or assembled the

wrong way

• A component not working properly

• Something missing – not logically complete

• Confusion from too many pieces in play

This is much easier to do on a realised working structure

because the structure does most of the work

An Analogy

We already have a tool

that breaks the four pieces

limit at the bottom of the

planning hierarchy – what

can we learn from that?

Critical Path Method

People built amazingly complex

structures before CPM, but no-

one shows you the failures, or

talks about the construction time

CPM –

MAX and MIN

Chartres

Gantt Charts

Before CPM there

were Gantt Charts

These helped a bit, by

providing the

scheduling problem

with a visual interface

But not enough, when

there are hundreds of

interlocking activities,

and interlocking in

ways other than time

Visualising a complex problem works if it is all in

one or two dimensions – whatever doesn’t fit is

ignored

Using CPM

Using CPM, we can

schedule projects with

thousands of activities

The machine stitches

together all the activities

into a network and

analyses it

We only need worry

about the detail around

each activity

Simple CPM simplifies the problem a bit – sometimes too much

Can we do something like CPM

with specifications and plans

- get a machine to stitch it all

together

- but not simplify something

that isn’t simple

CPM –

MAX and MIN

If we have done Project Management properly,

and merged cost and risk with time, and

provided for the interactions of activities to

switch other activities on and off – if we have

captured all the complexity, we are not too far

away from language

The Bad News

It is going to be a bit more difficult

• A specification defines its own terms, it refers to itself and

to other documents

• It can talk about any technical thing

• It can bring in objects, relations, groups, states, events,

existence, as well as times and resources

• It can be both broad concept and extremely detailed

The Good News A Function and Performance Specification is intended to:

• Describe what is required, rather than how to do it

• Be unambiguous

• Be consistent

• Be complete

• Use “dumbed down” language – only the “shalls” count

Sometimes it is necessary to fall back on the freedom of natural

language, because only it allows the seamless mixing of logic, groups,

objects and relations. It may only take a few words, but those few words

destroy the usefulness of any narrow, static approach (like tools with a

fixed and limited subset).

A + B = C CPM –

MAX and MIN

IF A + B = C THEN D + E = F

Consistent Evolution

Project

Activity

Relation

In Text

A secondary source

shall supply system time

We have come from CPM to

the semantics of text, with

the same technology

Building Document Structures

A large document may use a

million small undirected elements

in its structure.

We can try to build these large

complex structures by hand, but

then we run into the four pieces

limit, or we can build a machine

which builds structures - just like a

Jacquard loom, and for the same

reason

Self Extension

We need a machine which

uses an initial structure to

read text, extends its

structure as it does so,

then uses that structure to

read more text

It is all made out of the

same stuff – undirected

structures can be

seamlessly merged

Some FPS Examples

Tow Motor – 7 pages

SmartBus – 74 pages

Tow Motor

At this level of complexity (not much),

automated FPS analysis can show

errors, inconsistencies, ambiguities,

duplications, weak statements

Too simple to be an adequate test

Using The Structure

The words here are building a group – “Instrumentation within the cabin”

Slice And Dice

The instrumentation within the cabin

of the Tow Motor shall include a

tachometer.

AND

The instrumentation within the cabin

of the Tow Motor shall include an

engine hour meter.

…..

AND

All instrumentation shall be back-lit

and dimmable.

Building a group

Operating on a supergroup

Text is much more subtle than a database can support

There is an approach to Requirements Management which consists of

cutting the FPS into small pieces and putting them in a database, while

the systems aspects – the connections among the pieces - are ignored.

Using Background Knowledge

To Find Errors

Turning Circle “contains”

the turn relation of the vehicle

It looks like the FPS has a

value for Turning Radius,

when Turning Diameter

was meant

SmartBus

The SmartBus system is already a

system of interacting subsystems,

but the FPS is particularly dense

and complex, as it was based on the

performance of a commercial scale

trial system

We needed a complex FPS we could use as a test and talk about publicly. We came upon

the FPS years after the project was completed. The Victorian Department of Transport has

kindly permitted us to describe the results of automatic analysis.

Technicalities The FPS covers a wide range of technical issues:

Communications – Satellite, GPRS, Internet, RS232

Electronic components – microprocessors, LEDs, LCDs

States - Any time delay between the last instance of the Door Closure

event and the TOD event notionally represents “Unproductive Dwell At

Stop with Door Closed”

Bits of a bus – engine ignition and coolant, braking equipment, doors,

wheels, battery

Environment – standing in the sun, gravel bombardment, low hanging

branches, wash systems, vandalism, arc welding near electronics

Environmental testing – Temperature, Vibration, Mechanical and Thermal

Shock

It all seems daunting, until you see many of the same themes

repeating in other FPS

FPS Contents

The SmartBus FPS has the usual ingredients for an FPS of this size:

A block of defined terms at the front, a glossary at the back, with other

definitions scattered through the text

Subsystems described in separate sections, with document references

used for interlinking

Use of indexed lists and tables

It also has diagrams. Diagrams are not usually essential to an FPS, and

the system can do a lot without knowing what they show.

Local Dictionary

The defined terms require a dictionary that expands as the text is

read.

The system starts with about 20,000 words, access to another

200,000 about which it knows little more than their parts of speech,

and it has to accept new meanings, either for single or multiple

words – “up” and “down” get additional meanings.

Getting the definitions right is an important part of reading a large

FPS. Given the forward references, it is a hard job in itself.

Automated Assistant

A system to read complex documents

and build their semantic structures

allows people to concentrate on the

problem areas without getting lost in the

details – the four pieces limit is blown

away

Broadening the Application

This presentation has been directed to one document,

but once the structures are created,

it is easy to analyse among document structures

In any direction

Suggestions

• Make all the connections before beginning requirements

analysis, so all possible influences can be seen

• Accept that people have a limit on pieces of information

in play – don’t fight it, work out how to get around it

• Use inferences instead of statistics on something new

• Don’t use computer logic – it throws away too much

inferencing power

• Use tools which maintain the systems aspects

• Treat documents as machinery

The things that make it hard to do

are also the things

that make it worth doing

Interactive Engineering Pty Ltd

www.semanticstructure.com

Breaking Limits