Simulink^® Design Verifier™

Proof Objective

Define objectives that signals must satisfy when proving model properties

Library

Simulink Design Verifier

Description

When operating in property proving mode, the Simulink^® Design Verifier™ software proves that properties of your model satisfy specified criteria (see Proving Properties of a Model). In this mode, you can use Proof Objective blocks to define proof objectives for signals in your model. The Values parameter lets you specify values that a signal must achieve for at least one time step during a proof. The block applies the specified Values parameter to its input signal, and the Simulink Design Verifier software proves or disproves that the properties of your model satisfy specified criteria.

The block's parameter dialog box also allows you to

Enable or disable the objective.
Specify that the block should display its Values parameter in the model editor.
Specify that the block should display its output port.

Note The Simulink^® and Real-Time Workshop^® software ignore the Proof Objective block during model simulation and code generation, respectively. The Simulink Design Verifier software uses the Proof Objective block only when proving model properties.

Specifying Proof Objectives

Use the Values parameter to define values that a signal must achieve during a proof simulation. Specify any combination of scalars and intervals in the form of a MATLAB^® cell array (see Cell Arrays in the MATLAB documentation for information about working with cell arrays).

Tip If the Values parameter specifies only one scalar value, you do not need to enter it in the form of a MATLAB cell array.

Scalar values each comprise a single cell in the array, for example:

{0, 5}

A closed interval comprises a two-element vector as a cell in the array, where each element specifies an interval endpoint:

{[1, 2]}

Alternatively, you can specify scalar values using the Sldv.Point constructor, which accepts a single value as its argument. You can specify intervals using the Sldv.Interval constructor, which requires two input arguments, i.e., a lower bound and an upper bound for the interval. Optionally, you can provide one of the following strings as a third input argument that specifies inclusion or exclusion of the interval endpoints:

'()' — Defines an open interval.
'[]' — Defines a closed interval.
'(]' — Defines a left-open interval.
'[)' — Defines a right-open interval.

Note By default, Sldv.Interval considers an interval to be closed if you omit its third input argument.

As an example, the Values parameter

{0, [1, 3]}

specifies:

0 — a scalar
[1, 3] — a closed interval

The Values parameter

{Sldv.Interval(0, 1, '[)'), Sldv.Point(1)}

specifies:

Sldv.Interval(0, 1, '[)') — the right-open interval [0, 1)
Sldv.Point(1) — a scalar

If you specify multiple scalars and intervals for a Proof Objective block, the Simulink Design Verifier software combines them using a logical OR operation during the property proof. In this case, the software considers the entire proof objective to be satisfied if any single scalar or interval is satisfied.

Data Type Support

The Proof Objective block accepts signals of all built-in data types supported by the Simulink software. For a discussion on the data types supported by the Simulink software, see Data Types Supported by Simulink^® in Using Simulink^®.

Parameters and Dialog Box

Enable: Specify whether the block is enabled. If selected (the default), the Simulink Design Verifier software uses the block when proving properties of a model. Clearing this option disables the block, that is, causes the Simulink Design Verifier software to behave as if the Proof Objective block did not exist. If this option is not selected, the block appears grayed out in the model editor.
Type: Specify whether the block behaves as a Proof Objective or Test Objective block. Select Test Objective to transform the Proof Objective block into a Test Objective block.
Values: Specify the proof objective (see Specifying Proof Objectives).
Display values: Specify whether the block displays the contents of its Values parameter in the model editor. By default, this option is selected.
Pass through style: Specify whether the block displays an output port in the model editor. If selected (the default), the block displays its output port, allowing its input signal to pass through as the block output. If not selected, the block hides its output port and terminates the input signal. The following figure illustrates the appearance of the block in each case.