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  • Understanding evaluation of expressions containing '++' and '->' operators in C.

    - by Leif Ericson
    Consider this example: struct { int num; } s, *ps; s.num = 0; ps = &s; ++ps->num; printf("%d", s.num); /* Prints 1 */ It prints 1. So I understand that it is because according to operators precedence, -> is higher than ++, so the value ps->num (which is 0) is firstly fetched and then the ++ operator operates on it, so it increments it to 1. struct { int num; } s, *ps; s.num = 0; ps = &s; ps++->num; printf("%d", s.num); /* Prints 0 */ In this example I get 0 and I don't understand why; the explanation of the first example should be the same for this example. But it seems that this expression is evaluated as follows: At first, the operator ++ operates, and it operates on ps, so it increments it to the next struct. Only then -> operates and it does nothing because it just fetches the num field of the next struct and does nothing with it. But it contradicts the precedence of operators, which says that -> have higher precedence than ++. Can someone explain this behavior? Edit: After reading two answers which refer to a C++ precedence tables which indicate that a prefix ++/-- operators have lower precedence than ->, I did some googling and came up with this link that states that this rule applies also to C itself. It fits exactly and fully explains this behavior, but I must add that the table in this link contradicts a table in my own copy of K&R ANSI C. So if you have suggestions as to which source is correct I would like to know. Thanks.

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  • Unsure of how to get the right evaluation order

    - by Matt Fenwick
    I'm not sure what the difference between these two pieces of code is (with respect to x), but the first one completes: $ foldr (\x y -> if x == 4 then x else x + y) 0 [1,2 .. ] 10 and the second one doesn't (at least in GHCi): $ foldr (\x (y, n) -> if x == 4 then (x, n) else (x + y, n + 1)) (0, 0) [1,2 .. ] ....... What am I doing wrong that prevents the second example from completing when it hits x == 4, as in the first one? I've tried adding bang-patterns to both the x and to the x == 4 (inside a let) but neither seems to make a difference.

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  • Sharepoint 2010 web application development suitability evaluation/assessment

    - by Robert Koritnik
    I would like to know what kind of applications are suitable to be developed on top of Sharepoint 2010 and which should not be built on to of it. So when to embrace/avoid Sharepoint 2010 as a development platform for new web applications. Addendum Would you as a sharepoint development specialist choose it as a platform for your next enterprise application with these characteristics: processor intensive lots of various screens for entering and managing data many complex business processes no need to change the UI (ie. reposition parts) ERP integration etc. I'm an Asp.net MVC (former web forms) developer and would like to know if usual multi-page semi complex web applications (intra/extra-net) should be built on top of Sharepoint 2010 and why (if yes or if no).

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  • Evaluation of (de)reference operators

    - by Micha
    I have an (uncommented...) source file which I'm trying to understand. static const Map *gCurMap; static std::vector<Map> mapVec; then auto e = mapVec.end(); auto i = mapVec.begin(); while(i!=e) { // ... const Map *map = gCurMap = &(*(i++)); // ... } I don't understand what &(*(i++)) does. It does not compile when just using i++, but to me it looks the same, because I'm "incrementing" i, then I'm requesting the value at the given address and then I'm requesting the address of this value?!

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  • NDepend Evaluation: Part 3

    - by Anthony Trudeau
    NDepend is a Visual Studio add-in designed for intense code analysis with the goal of high code quality. NDepend uses a number of metrics and aggregates the data in pleasing static and active visual reports. My evaluation of NDepend will be broken up into several different parts. In the first part of the evaluation I looked at installing the add-in.  And in the last part I went over my first impressions including an overview of the features.  In this installment I provide a little more detail on a few of the features that I really like. Dependency Matrix The dependency matrix is one of the rich visual components provided with NDepend.  At a glance it lets you know where you have coupling problems including cycles.  It does this with number indicating the weight of the dependency and a color-coding that indicates the nature of the dependency. Green and blue cells are direct dependencies (with the difference being whether the relationship is from row-to-column or column-to-row).  Black cells are the ones that you really want to know about.  These indicate that you have a cycle.  That is, type A refers to type B and type B also refers to Type A. But, that’s not the end of the story.  A handy pop-up appears when you hover over the cell in question.  It explains the color, the dependency, and provides several interesting links that will teach you more than you want to know about the dependency. You can double-click the problem cells to explode the dependency.  That will show the dependencies on a method-by-method basis allowing you to more easily target and fix the problem.  When you’re done you can click the back button on the toolbar. Dependency Graph The dependency graph is another component provided.  It’s complementary to the dependency matrix, but it isn’t as easy to identify dependency issues using the window. On a positive note, it does provide more information than the matrix. My biggest issue with the dependency graph is determining what is shown.  This was not readily obvious.  I ended up using the navigation buttons to get an acceptable view.  I would have liked to choose what I see. Once you see the types you want you can get a decent idea of coupling strength based on the width of the dependency lines.  Double-arrowed lines are problematic and are shown in red.  The size of the boxes will be related to the metric being displayed.  This is controlled using the Box Size drop-down in the toolbar.  Personally, I don’t find the size of the box to be helpful, so I change it to Constant Font. One nice thing about the display is that you can see the entire path of dependencies when you hover over a type.  This is done by color-coding the dependencies and dependants.  It would be nice if selecting the box for the type would lock the highlighting in place. I did find a perhaps unintended work-around to the color-coding.  You can lock the color-coding in by hovering over the type, right-clicking, and then clicking on the canvas area to clear the pop-up menu.  You can then do whatever with it including saving it to an image file with the color-coding. CQL NDepend uses a code query language (CQL) to work with your code just like it was a database.  CQL cannot be confused with the robustness of T-SQL or even LINQ, but it represents an impressive attempt at providing an expressive way to enumerate and interrogate your code. There are two main windows you’ll use when working with CQL.  The CQL Query Explorer allows you to define what queries (rules) are run as part of a report – I immediately unselected rules that I don’t want in my results.  The CQL Query Edit window is where you can view or author your own rules.  The explorer window is pretty self-explanatory, so I won’t mention it further other than to say that any queries you author will appear in the custom group. Authoring your own queries is really hard to screw-up.  The Intellisense-like pop-ups tell you what you can do while making composition easy.  I was able to create a query within two minutes of playing with the editor.  My query warns if any types that are interfaces don’t start with an “I”. WARN IF Count > 0 IN SELECT TYPES WHERE IsInterface AND !NameLike “I” The results from the CQL Query Edit window are immediate. That fact makes it useful for ad hoc querying.  It’s worth mentioning two things that could make the experience smoother.  First, out of habit from using Visual Studio I expect to be able to scroll and press Tab to select an item in the list (like Intellisense).  You have to press Enter when you scroll to the item you want.  Second, the commands are case-sensitive.  I don’t see a really good reason to enforce that. CQL has a lot of potential not just in enforcing code quality, but also enforcing architectural constraints that your enterprise has defined. Up Next My next update will be the final part of the evaluation.  I will summarize my experience and provide my conclusions on the NDepend add-in. ** View Part 1 of the Evaluation ** ** View Part 2 of the Evaluation ** Disclaimer: Patrick Smacchia contacted me about reviewing NDepend. I received a free license in return for sharing my experiences and talking about the capabilities of the add-in on this site. There is no expectation of a positive review elicited from the author of NDepend.

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  • Expected time for lazy evaluation with nested functions?

    - by Matt_JD
    A colleague and I are doing a free R course, although I believe this is a more general lazy evaluation issue, and have found a scenario that we have discussed briefly and I'd like to find out the answer from a wider community. The scenario is as follows (pseudo code): wrapper => function(thing) { print => function() { write(thing) } } v = createThing(1, 2, 3) w = wrapper(v) v = createThing(4, 5, 6) w.print() // Will print 4, 5, 6 thing. v = create(7, 8, 9) w.print() // Will print 4, 5, 6 because "thing" has now been evaluated. Another similar situation is as follows: // Using the same function as above v = createThing(1, 2, 3) v = wrapper(v) w.print() // The wrapper function incestuously includes itself. Now I understand why this happens but where my colleague and I differ is on what should happen. My colleague's view is that this is a bug and the evaluation of the passed in argument should be forced at the point it is passed in so that the returned "w" function is fixed. My view is that I would prefer his option myself, but that I realise that the situation we are encountering is down to lazy evaluation and this is just how it works and is more a quirk than a bug. I am not actually sure of what would be expected, hence the reason I am asking this question. I think that function comments could express what will happen, or leave it to be very lazy, and if the coder using the function wants the argument evaluated then they can force it before passing it in. So, when working with lazy evaulation, what is the practice for the time to evaluate an argument passed, and stored, inside a function?

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  • Lazy Evaluation &ndash; Why being lazy in F# blows my mind!

    - by MarkPearl
    First of all – shout out to Peter Adams – from the feedback I have gotten from him on the last few posts of F# that I have done – my mind has just been expanded. I did a blog post a few days ago about infinite sequences – I didn’t really understand what was going on with it, and I still don’t really get it – but I am getting closer. In Peter’s last comment he made mention of Lazy Evaluation. I am ashamed to say that up till then I had never heard about lazy evaluation – how can evaluation be lazy? I mean, I know about lazy loading and that makes sense… but surely something is either evaluated or not! Well… a bit of reading today and I have been enlightened to a point – if you do know of any good articles explaining lazy evaluation please send them to me. So what is lazy evaluation and why is it useful? Lazy evaluation is a process whereby the system only computes the values needed and “ignores” the computations not needed. I’m going out on a limb here, but with this explanation in hand, imagine the following C# code… public int CalculatedVal() { int Val1 = 0; int Val2 = 0; for (int Count = 0; Count < 1000000; Count++) { Val1++; } return Val2; }   Normally, even though Val1 is never needed, the system would loop 1000000 times and add 1 to the current value of Val1. Imagine if the system realized this and so just skipped this segment of code and instead did the following…. public int CalculatedVal() { int Val1 = 0; return Val2; }   A massive saving in computation and wasted effort. Now I am pretty sure it isn’t as simple as this but I think this is the basic idea. For a more detailed explanation of lazy evaluation in c#, Pedram Rezei has a wonderful post on lazy evaluation and makes some C# comparisons. I am not going to take any thunder from him by repeating everything he said since I think he did such a good job of explaining it himself. What I am interested in though is how in F# do you tell something to have lazy evalution, and how do you know if something will be eager or lazy by looking at it. I found this post was useful. From reading around F# by default uses eager evaluation unless explicitly told to use lazy evaluation. One exception to this is sequences, which are lazy by default. Now reading about lazy evaluation has helped me understand more about F# coding… From my understanding of F# because of its declarative nature, most of the actual code you are declaring properties and rules – very little code is actually saying do this right now - but when it comes to a “do this” code section, it then evaluates and optimizes code and applies the rules. So props to lazy evaluation and its optimizations…

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  • Why is the order of evaluation for function parameters undefined in c++?

    - by kunj2aan
    The standard doesn't specify the order of evaluation of arguments with this line: The order of evaluation of arguments is unspecified. What does Better code can be generated in the absence of restrictions on expression evaluation order imply? What is the drawback in asking all the compilers to evaluate the function arguments Left to Right for example? What kinds of optimizations do compilers perform because of this undefined spec?

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  • understanding evaluation function

    - by mish
    I am developing a chess program. And have made use of an alpha beta algorithm and a static evaluation function. I have successfully implemented both but I want to improve the evaluation function by automatically tuning the weights assigned to its features. At this point am totally confused about the policy suitable for updating the weights of the function. One policy I have in mind is to check whether a move is good or bad before updating weights but I really know how to implement it. Thus I need ideas and pseudo code please.

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  • Software Architecture and Software Architecture Evaluation

    How many of us have worked at places where the concept of software architecture was ridiculed for wasting time and money? Even more ridiculous to them was the concept of evaluating software architecture. I think the next time that I am in this situation again, and I hope that I never am I will have to push for this methodology in the software development life cycle. I have spent way too many hours/days/months/years working poorly architected systems or systems that were just built ADHOC. This in software development must stop. I can understand why systems get like this due to overzealous sales staff, demanding management that wants everything yesterday, and project managers asking if things are done yet before the project has even started. But seriously, some time must be spent designing the applications that we write along with evaluating the architecture so that it will integrate will within the existing systems of an origination. If placed in this situation again, I will strive to gain buying from key players within the business, for example: Senior Software Engineers\Developers, Software Architects, Project Managers, Software Quality Assurance, Technical Services, Operations, and Finance in order for this idea to succeed with upper management. In order to convince these key players I will have to show them the benefits of architecture and even more benefits of evaluating software architecture on a system wide level. Benefits of Software Architecture Evaluation Places Stakeholders in the Same Room to Communicate Ensures Delivery of Detailed Quality Goals Prioritizes Conflicting Goals Requires Clear Explication Improves the Quality of Documentation Discovers Opportunities for Cross-Project Reuse Improves Architecture Practices Once I had key player buy in then and only then would I approach upper management about my plan regarding implementing the concept of software architecture and using evaluation to ensure that the software being designed is the proper architecture for the project. In addition to the benefits listed above I would also show upper management how much time is being wasted by not doing these evaluations. For example, if project X cost us Y amount, then why do we have several implementations in various forms of X and how much money and time could we have saved if we just reused the existing code base to give each system the same functionality that was already created? After this, I would mention what would happen if we had 50 instances of this situation? Then I would show them how the software architecture evaluation process would have prevented this and that the optimization could have leveraged its existing code base to increase the speed and quality of its development. References:Carnegie Mellon Software Engineering Institute (2011). Architecture Tradeoff Analysis Method from http://www.sei.cmu.edu/architecture/tools/evaluate/atam.cfm

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  • How to write an R function that evaluates an expression within a data-frame

    - by Prasad Chalasani
    Puzzle for the R cognoscenti: Say we have a data-frame: df <- data.frame( a = 1:5, b = 1:5 ) I know we can do things like with(df, a) to get a vector of results. But how do I write a function that takes an expression (such as a or a > 3) and does the same thing inside. I.e. I want to write a function fn that takes a data-frame and an expression as arguments and returns the result of evaluating the expression "within" the data-frame as an environment. Never mind that this sounds contrived (I could just use with as above), but this is just a simplified version of a more complex function I am writing. I tried several variants ( using eval, with, envir, substitute, local, etc) but none of them work. For example if I define fn like so: fn <- function(dat, expr) { eval(expr, envir = dat) } I get this error: > fn( df, a ) Error in eval(expr, envir = dat) : object 'a' not found Clearly I am missing something subtle about environments and evaluation. Is there a way to define such a function?

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  • Deferred execution and eager evaluation

    - by babu M
    Hi Could you please give me an example for Deferred execution with eager evaluation in C#? I read from MSDN that deferred execution in LINQ can be implemented either with lazy or eager evaluation...i could find examples in the internet for Deferred execution with lazy evaluation ,however i could not find any example for Deferred execution with eager evaluation....please help me....its urgent... Moreover,how deferred execution differs from lazy evaluation?In my point of view,both are looking same.Could you please provide any example for this too?

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  • Evaluating Oracle Data Mining Has Never Been Easier - Evaluation "Kit" Available

    - by chberger
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Now you can quickly and easily get set up to starting using Oracle Data Mining for evaluation purposes. Just go to the Oracle Technology Network (OTN) and follow these simple steps. Oracle Data Mining Evaluation "Kit" Instructions Step 1: Download and Install the Oracle Database 11g Release 2 Anyone can download and install the Oracle Database for free for evaluation purposes. Read OTN web site for details. 11.2.0.1.0 DB is the minimum, 11.2.0.2 is better and naturally 11.2.0.3 is best if you are a current customer and on active support. Either 32-bit or 64-bit is fine. 4GB of RAM or more works fine for SQL Developer and the Oracle Data Miner GUI extension. Downloading the database and installing it should take just about an hour or so, depending on your network and computer. For more instructions on setting up Oracle Data Mining see: http://www.oracle.com/technetwork/database/options/odm/dataminerworkflow-168677.html When you install the Oracle Database, the Sample Examples data should also be installed e.g.:Release 2 Examples win32_11gR2_examples.zip (565,154,740 bytes). Contains examples of how to use the Oracle Database. Download if you are new to Oracle and want to try some of the examples presented in the Documentation Step 2: Install SQL Developer 3.1 (the Oracle Data Mining Extension installs automatically) Step 3. Follow the four free step-by-step Oracle-by-Examples e-training lessons: Setting Up Oracle Data Miner 11g Release 2 This tutorial covers the process of setting up Oracle Data Miner 11g Release 2 for use within Oracle SQL Developer 3.0. Using Oracle Data Miner 11g Release 2 This tutorial covers the use of Oracle Data Miner to perform data mining against Oracle Database 11g Release 2. In this lesson, you examine and solve a data mining business problem by using the Oracle Data Miner graphical user interface (GUI). Star Schema Mining Using Oracle Data Miner This tutorial covers the use of Oracle Data Miner to perform star schema mining against Oracle Database 11g Release 2. Text Mining Using Oracle Data Miner This tutorial covers the use of Oracle Data Miner to perform text mining against Oracle Database 11g Release 2. That’s it! Easy, fun and the fastest way to get started evaluating Oracle Data Mining. Enjoy! Charlie

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  • Microsoft propose une version d'évaluation gratuite de Project 2010 et des vidéos de présentation de

    Mise à jour du 11/06/10 Microsoft propose une version d'évaluation gratuite de Project 2010 Et des vidéos de présentation de son outil de gestion de projet Project est certainement un des produits les plus méconnus de Microsoft. Pourtant, cette application spécialisée pour la gestion de projet ne manque pas de qualités. Il peut, dans bien des cas, faire économiser un temps précieux aux développeurs qui souhaitent développer et non pas passer leurs journées à organiser ou à planifier des tâches pour les autres. Pour remédier à ce relatif anonymat de Project, Microsoft a décidé de proposer

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  • SAF Evaluation part II the Formal Methods

    OnI talked about evaluating a candidate architecture in code. This post is dedicated to evaluation on paper.I remember one system I was working on, I was keen on making the architecture asynchronous and message oriented (it was all circa 2001 by the way) However, I was new on the team and my role (as the [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • SAF Architecture Evaluation (Introduction)

    I saidin “what’s Software architecture” – architecture is both an early artifact and it also represents the significant decisions about the system – or to sum it up”Architecture is the decisions that youwishyou could get right early in a project.(Ralph Johnston*). That is exactly why I made evaluation one of the key steps in SAF. [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Website Performance Evaluation

    A website performance evaluation begins with a review of key indicators. The key indicators offer a snapshot of the websites overall performance and a high-level view of areas that need improvement.

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  • Microsoft Offers Evaluation Kit for 2010 Products

    Microsoft is offering a kit designed to streamline the evaluation process for orgs considering its new software products....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • R matrix handling expressions aren't evaluated in a function or a "for" loop - Column extract doesn't seem to work

    - by Sal Leggio
    I have an R matrix named ddd. When I enter this, everything works fine: i <- 1 shapiro.test(ddd[,y]) ad.test(ddd[,y]) stem(ddd[,y]) print(y) The calls to Shapiro Wilk, Anderson Darling, and stem all work, and extract the same column. If I put this code in a "for" loop, the calls to Shapiro Wilk, and Anderson Darling stop working, while the the stem & leaf call and the print call continue to work. for (y in 7:10) { shapiro.test(ddd[,y]) ad.test(ddd[,y]) stem(ddd[,y]) print(y) } The decimal point is 1 digit(s) to the right of the | 0 | 0 0 | 899999 1 | 0 [1] 7 The same thing happens if I try and write a function. SW & AD do not work. The other calls do. D <- function (y) { + shapiro.test(ddd[,y]) + ad.test(ddd[,y]) + stem(ddd[,y]) + print(y) } D(9) The decimal point is at the | 9 | 000 9 | 10 | 00000 [1] 9 Why don't all the calls behave the same way?

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  • Puppet:get real-time status of catalog evaluation and post to remote server

    - by txworking
    According to this article http://docs.puppetlabs.com/guides/puppet_internals.html There are four phases when puppet agent got a catalog from master. resource generation = relationships = evaluation = reporting Reporting As the transaction progresses, it collects logs and metrics on what it does. At the end of evaluation, it turns this information into a report, which it sends to the server (if requested). And at the end of evaluation puppet agent would generate a report and sent the report to the master. Is there a way to get real-time status of evaluation phase and post them to a remote logcollector? Glad for any suggestions.

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  • Windows 7 Enterprise : Microsoft sort une version d'évaluation gratuite de l'édition "réservée aux professionnels de l'informatique"

    Microsoft propose une version d'évaluation gratuite de Windows 7 Enterprise Que pensez-vous de cette édition spécialement dédiée aux professionnels de l'informatique Le 8 avril 2014, Windows XP sera de l'histoire ancienne pour Microsoft. Plus aucune mise à jour et plus aucun support ne seront proposés pour le système d'exploitation n°1 dans le monde. Vista a suivi mais a déboussolé tant d'utilisateurs que pour beaucoup de professionnels IT, le vrai successeur de Windows XP est en fait Windows 7. Et plus exactement Windows 7 Enterprise. Au moment où Microsoft vient de lancer une offre spéciale de 90 jours d'essai gratuit pour cette édition spéciale (justement en rapport avec...

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  • How do I create a good evaluation function for a new board game?

    - by A. Rex
    I write programs to play board game variants sometimes. The basic strategy is standard alpha-beta pruning or similar searches, sometimes augmented by the usual approaches to endgames or openings. I've mostly played around with chess variants, so when it comes time to pick my evaluation function, I use a basic chess evaluation function. However, now I am writing a program to play a completely new board game. How do I choose a good or even decent evaluation function? The main challenges are that the same pieces are always on the board, so a usual material function won't change based on position, and the game has been played less than a thousand times or so, so humans don't necessarily play it enough well yet to give insight. (PS. I considered a MoGo approach, but random games aren't likely to terminate.) Any ideas? Game details: The game is played on a 10-by-10 board with a fixed six pieces per side. The pieces have certain movement rules, and interact in certain ways, but no piece is ever captured. The goal of the game is to have enough of your pieces in certain special squares on the board. The goal of the computer program is to provide a player which is competitive with or better than current human players.

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